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+# SimpleNote Web - Reusable Components
+
+Component library for SimpleNote Web. All components use CSS custom properties for theming.
+
+---
+
+## 1. Buttons
+
+### 1.1 Primary Button
+```html
+<button class="btn btn-primary">Save</button>
+```
+```css
+.btn-primary {
+  background: var(--color-accent);
+  color: var(--color-bg);
+  border: none;
+  padding: 0.5rem 1rem;
+  border-radius: 6px;
+  font-weight: 600;
+  cursor: pointer;
+  transition: background 0.15s, transform 0.1s;
+}
+.btn-primary:hover { background: var(--color-accent-hover); }
+.btn-primary:active { transform: scale(0.98); }
+.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }
+```
+
+### 1.2 Secondary Button
+```html
+<button class="btn btn-secondary">Cancel</button>
+```
+```css
+.btn-secondary {
+  background: transparent;
+  color: var(--color-text);
+  border: 1px solid var(--color-border);
+  padding: 0.5rem 1rem;
+  border-radius: 6px;
+  cursor: pointer;
+  transition: background 0.15s, border-color 0.15s;
+}
+.btn-secondary:hover {
+  background: var(--color-hover);
+  border-color: var(--color-text-muted);
+}
+```
+
+### 1.3 Ghost Button (icon-only)
+```html
+<button class="btn btn-ghost" aria-label="Edit">
+  <svg><!-- pencil icon --></svg>
+</button>
+```
+```css
+.btn-ghost {
+  background: transparent;
+  border: none;
+  color: var(--color-text-muted);
+  padding: 0.5rem;
+  border-radius: 6px;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  transition: background 0.15s, color 0.15s;
+}
+.btn-ghost:hover {
+  background: var(--color-hover);
+  color: var(--color-text);
+}
+```
+
+### 1.4 Danger Button
+```html
+<button class="btn btn-danger">Delete</button>
+```
+```css
+.btn-danger {
+  background: var(--color-danger);
+  color: white;
+  border: none;
+  padding: 0.5rem 1rem;
+  border-radius: 6px;
+  font-weight: 600;
+  cursor: pointer;
+}
+.btn-danger:hover { background: var(--color-danger-hover); }
+```
+
+### 1.5 Icon Button with Label
+```html
+<button class="btn btn-icon-label">
+  <svg><!-- plus icon --></svg>
+  <span>New Doc</span>
+</button>
+```
+```css
+.btn-icon-label {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  background: var(--color-accent);
+  color: var(--color-bg);
+  border: none;
+  padding: 0.5rem 1rem;
+  border-radius: 6px;
+  font-weight: 600;
+  cursor: pointer;
+}
+```
+
+---
+
+## 2. Inputs
+
+### 2.1 Text Input
+```html
+<div class="input-group">
+  <label for="title">Title</label>
+  <input type="text" id="title" class="input" placeholder="Document title...">
+</div>
+```
+```css
+.input-group {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+.input-group label {
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: var(--color-text-muted);
+}
+.input {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  color: var(--color-text);
+  padding: 0.625rem 0.875rem;
+  border-radius: 6px;
+  font-size: 1rem;
+  transition: border-color 0.15s, box-shadow 0.15s;
+}
+.input:focus {
+  outline: none;
+  border-color: var(--color-accent);
+  box-shadow: 0 0 0 3px var(--color-accent-alpha);
+}
+.input::placeholder { color: var(--color-text-muted); }
+.input:disabled { opacity: 0.5; cursor: not-allowed; }
+.input.error { border-color: var(--color-danger); }
+```
+
+### 2.2 Search Input
+```html
+<div class="search-input">
+  <svg class="search-icon"><!-- search icon --></svg>
+  <input type="text" placeholder="Search..." class="input">
+  <button class="search-clear" aria-label="Clear">✕</button>
+</div>
+```
+```css
+.search-input {
+  position: relative;
+  display: flex;
+  align-items: center;
+}
+.search-input .input {
+  padding-left: 2.5rem;
+  padding-right: 2.5rem;
+  width: 100%;
+}
+.search-icon {
+  position: absolute;
+  left: 0.75rem;
+  color: var(--color-text-muted);
+  pointer-events: none;
+}
+.search-clear {
+  position: absolute;
+  right: 0.5rem;
+  background: transparent;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  padding: 0.25rem;
+  border-radius: 4px;
+  display: none;
+}
+.search-input.has-value .search-clear { display: block; }
+.search-clear:hover { color: var(--color-text); }
+```
+
+### 2.3 Select / Dropdown
+```html
+<div class="select-group">
+  <label for="type">Type</label>
+  <select id="type" class="select">
+    <option value="requirement">Requirement</option>
+    <option value="note">Note</option>
+    <option value="spec">Specification</option>
+    <option value="general">General</option>
+  </select>
+</div>
+```
+```css
+.select {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  color: var(--color-text);
+  padding: 0.625rem 2rem 0.625rem 0.875rem;
+  border-radius: 6px;
+  font-size: 1rem;
+  cursor: pointer;
+  appearance: none;
+  background-image: url("data:image/svg+xml,...");
+  background-repeat: no-repeat;
+  background-position: right 0.75rem center;
+  background-size: 1rem;
+}
+.select:focus {
+  outline: none;
+  border-color: var(--color-accent);
+  box-shadow: 0 0 0 3px var(--color-accent-alpha);
+}
+```
+
+### 2.4 Tags Input (Chip-style)
+```html
+<div class="tags-input" id="tags-input">
+  <div class="tags-chips">
+    <span class="tag-chip">
+      backend
+      <button class="tag-remove" data-tag="backend">×</button>
+    </span>
+    <span class="tag-chip">
+      api
+      <button class="tag-remove" data-tag="api">×</button>
+    </span>
+  </div>
+  <input type="text" class="tags-input-field" placeholder="Add tag...">
+</div>
+```
+```css
+.tags-input {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.5rem;
+  padding: 0.5rem;
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: 6px;
+  min-height: 42px;
+}
+.tags-input:focus-within {
+  border-color: var(--color-accent);
+  box-shadow: 0 0 0 3px var(--color-accent-alpha);
+}
+.tags-chips { display: flex; flex-wrap: wrap; gap: 0.5rem; }
+.tag-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.25rem;
+  background: var(--color-accent-alpha);
+  color: var(--color-accent);
+  padding: 0.25rem 0.5rem;
+  border-radius: 4px;
+  font-size: 0.875rem;
+}
+.tag-remove {
+  background: transparent;
+  border: none;
+  color: inherit;
+  cursor: pointer;
+  padding: 0;
+  font-size: 1rem;
+  line-height: 1;
+}
+.tag-remove:hover { color: var(--color-danger); }
+.tags-input-field {
+  flex: 1;
+  min-width: 100px;
+  background: transparent;
+  border: none;
+  color: var(--color-text);
+  padding: 0.25rem;
+  font-size: 0.875rem;
+}
+.tags-input-field:focus { outline: none; }
+```
+
+### 2.5 Textarea (Markdown Editor)
+```html
+<textarea class="textarea-editor" id="editor" rows="20">
+## Markdown content
+</textarea>
+```
+```css
+.textarea-editor {
+  width: 100%;
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  color: var(--color-text);
+  padding: 1rem;
+  border-radius: 6px;
+  font-family: var(--font-mono);
+  font-size: 0.9375rem;
+  line-height: 1.6;
+  resize: vertical;
+  tab-size: 2;
+}
+.textarea-editor:focus {
+  outline: none;
+  border-color: var(--color-accent);
+  box-shadow: 0 0 0 3px var(--color-accent-alpha);
+}
+```
+
+---
+
+## 3. Cards
+
+### 3.1 Document Card
+```html
+<article class="doc-card" data-id="uuid">
+  <div class="doc-card-header">
+    <span class="doc-type-badge">REQ</span>
+    <h3 class="doc-title">API Authentication Design</h3>
+  </div>
+  <div class="doc-tags">
+    <button class="tag-pill" data-tag="backend">backend</button>
+    <button class="tag-pill" data-tag="api">api</button>
+    <button class="tag-pill" data-tag="auth">auth</button>
+  </div>
+  <div class="doc-meta">
+    <span class="doc-date">📅 Mar 28</span>
+    <span class="doc-author">👤 agent-001</span>
+    <span class="doc-status status-draft">✓ draft</span>
+    <span class="doc-priority priority-high">🔴 high</span>
+  </div>
+</article>
+```
+```css
+.doc-card {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: 8px;
+  padding: 1rem;
+  cursor: pointer;
+  transition: border-color 0.15s, box-shadow 0.15s, transform 0.1s;
+}
+.doc-card:hover {
+  border-color: var(--color-accent);
+  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
+  transform: translateY(-1px);
+}
+.doc-card-header {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  margin-bottom: 0.75rem;
+}
+.doc-type-badge {
+  background: var(--color-accent-alpha);
+  color: var(--color-accent);
+  font-size: 0.75rem;
+  font-weight: 700;
+  padding: 0.125rem 0.5rem;
+  border-radius: 4px;
+  flex-shrink: 0;
+}
+.doc-title {
+  font-size: 1rem;
+  font-weight: 600;
+  color: var(--color-text);
+  margin: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.doc-tags {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.5rem;
+  margin-bottom: 0.75rem;
+}
+.doc-meta {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.75rem;
+  font-size: 0.8125rem;
+  color: var(--color-text-muted);
+}
+```
+
+### 3.2 Library Card
+```html
+<article class="lib-card" data-id="uuid">
+  <div class="lib-icon">📁</div>
+  <div class="lib-info">
+    <h3 class="lib-name">Backend Requirements</h3>
+    <span class="lib-count">12 documents · 3 sub-libraries</span>
+  </div>
+  <button class="btn-ghost lib-menu" aria-label="Library menu">⋯</button>
+</article>
+```
+```css
+.lib-card {
+  display: flex;
+  align-items: center;
+  gap: 1rem;
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: 8px;
+  padding: 1rem;
+  cursor: pointer;
+  transition: background 0.15s;
+}
+.lib-card:hover { background: var(--color-hover); }
+.lib-icon { font-size: 1.5rem; }
+.lib-info { flex: 1; min-width: 0; }
+.lib-name {
+  font-size: 1rem;
+  font-weight: 600;
+  margin: 0 0 0.25rem;
+}
+.lib-count { font-size: 0.8125rem; color: var(--color-text-muted); }
+```
+
+---
+
+## 4. Tags & Badges
+
+### 4.1 Tag Pill (Clickable)
+```html
+<button class="tag-pill" data-tag="backend">backend</button>
+```
+```css
+.tag-pill {
+  background: var(--color-accent-alpha);
+  color: var(--color-accent);
+  border: none;
+  padding: 0.25rem 0.625rem;
+  border-radius: 9999px;
+  font-size: 0.8125rem;
+  cursor: pointer;
+  transition: background 0.15s, transform 0.1s;
+}
+.tag-pill:hover {
+  background: var(--color-accent);
+  color: var(--color-bg);
+  transform: scale(1.05);
+}
+.tag-pill.active {
+  background: var(--color-accent);
+  color: var(--color-bg);
+}
+```
+
+### 4.2 Status Badge
+```html
+<span class="status-badge status-draft">draft</span>
+<span class="status-badge status-approved">approved</span>
+<span class="status-badge status-implemented">implemented</span>
+```
+```css
+.status-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.25rem;
+  padding: 0.125rem 0.5rem;
+  border-radius: 4px;
+  font-size: 0.75rem;
+  font-weight: 600;
+  text-transform: uppercase;
+}
+.status-draft {
+  background: var(--color-warning-bg);
+  color: var(--color-warning);
+}
+.status-approved {
+  background: var(--color-info-bg);
+  color: var(--color-info);
+}
+.status-implemented {
+  background: var(--color-success-bg);
+  color: var(--color-success);
+}
+```
+
+### 4.3 Priority Indicator
+```html
+<span class="priority priority-high" title="High priority">🔴</span>
+<span class="priority priority-medium" title="Medium priority">🟡</span>
+<span class="priority priority-low" title="Low priority">🟢</span>
+```
+```css
+.priority { font-size: 0.875rem; }
+```
+
+### 4.4 Type Badge
+```html
+<span class="type-badge type-requirement">REQ</span>
+<span class="type-badge type-note">NOTE</span>
+<span class="type-badge type-spec">SPEC</span>
+<span class="type-badge type-general">DOC</span>
+```
+```css
+.type-badge {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  padding: 0.125rem 0.375rem;
+  border-radius: 4px;
+  font-size: 0.6875rem;
+  font-weight: 700;
+  letter-spacing: 0.05em;
+}
+.type-requirement { border-color: var(--color-accent); color: var(--color-accent); }
+.type-note { border-color: var(--color-info); color: var(--color-info); }
+.type-spec { border-color: var(--color-purple); color: var(--color-purple); }
+.type-general { border-color: var(--color-text-muted); color: var(--color-text-muted); }
+```
+
+---
+
+## 5. Navigation
+
+### 5.1 Sidebar
+```html
+<aside class="sidebar">
+  <div class="sidebar-section">
+    <h4 class="sidebar-title">📁 Libraries</h4>
+    <nav class="library-tree">
+      <!-- Tree items -->
+    </nav>
+  </div>
+  <div class="sidebar-section">
+    <h4 class="sidebar-title">🏷️ Tags</h4>
+    <nav class="tag-list">
+      <!-- Tag items -->
+    </nav>
+  </div>
+</aside>
+```
+```css
+.sidebar {
+  width: 280px;
+  height: 100%;
+  background: var(--color-surface);
+  border-right: 1px solid var(--color-border);
+  overflow-y: auto;
+  padding: 1rem;
+  display: flex;
+  flex-direction: column;
+  gap: 1.5rem;
+}
+.sidebar-section { display: flex; flex-direction: column; gap: 0.5rem; }
+.sidebar-title {
+  font-size: 0.75rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+  color: var(--color-text-muted);
+  margin: 0;
+}
+@media (max-width: 768px) {
+  .sidebar {
+    display: none; /* Hidden on mobile, shown via bottom nav */
+  }
+}
+```
+
+### 5.2 Library Tree Item
+```html
+<div class="tree-item tree-item-library" data-id="uuid">
+  <button class="tree-toggle" aria-expanded="true">▼</button>
+  <span class="tree-icon">📁</span>
+  <span class="tree-name">Backend Requirements</span>
+  <span class="tree-count">(12)</span>
+</div>
+<div class="tree-children" style="display: block;">
+  <!-- Nested items -->
+</div>
+```
+```css
+.tree-item {
+  display: flex;
+  align-items: center;
+  gap: 0.375rem;
+  padding: 0.375rem 0.5rem;
+  border-radius: 6px;
+  cursor: pointer;
+  font-size: 0.875rem;
+  color: var(--color-text);
+}
+.tree-item:hover { background: var(--color-hover); }
+.tree-item.active { background: var(--color-accent-alpha); color: var(--color-accent); }
+.tree-toggle {
+  background: transparent;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  padding: 0;
+  font-size: 0.625rem;
+  width: 1rem;
+  transition: transform 0.15s;
+}
+.tree-toggle.collapsed { transform: rotate(-90deg); }
+.tree-icon { font-size: 1rem; }
+.tree-name { flex: 1; }
+.tree-count { color: var(--color-text-muted); font-size: 0.75rem; }
+.tree-children {
+  padding-left: 1.25rem;
+  border-left: 1px solid var(--color-border);
+  margin-left: 0.625rem;
+}
+```
+
+### 5.3 Breadcrumbs
+```html
+<nav class="breadcrumbs" aria-label="Breadcrumb">
+  <a href="#" class="breadcrumb">Home</a>
+  <span class="breadcrumb-sep">/</span>
+  <a href="#" class="breadcrumb">Backend</a>
+  <span class="breadcrumb-sep">/</span>
+  <span class="breadcrumb-current">API</span>
+</nav>
+```
+```css
+.breadcrumbs {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  font-size: 0.875rem;
+  flex-wrap: wrap;
+}
+.breadcrumb {
+  color: var(--color-text-muted);
+  text-decoration: none;
+}
+.breadcrumb:hover { color: var(--color-accent); }
+.breadcrumb-sep { color: var(--color-border); }
+.breadcrumb-current {
+  color: var(--color-text);
+  font-weight: 500;
+}
+```
+
+### 5.4 Bottom Navigation (Mobile)
+```html
+<nav class="bottom-nav">
+  <button class="bottom-nav-item active">
+    <svg><!-- home icon --></svg>
+    <span>Home</span>
+  </button>
+  <button class="bottom-nav-item">
+    <svg><!-- folder icon --></svg>
+    <span>Libraries</span>
+  </button>
+  <button class="bottom-nav-item bottom-nav-item-primary">
+    <svg><!-- plus icon --></svg>
+  </button>
+  <button class="bottom-nav-item">
+    <svg><!-- settings icon --></svg>
+    <span>Settings</span>
+  </button>
+</nav>
+```
+```css
+.bottom-nav {
+  display: none;
+  position: fixed;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  background: var(--color-surface);
+  border-top: 1px solid var(--color-border);
+  padding: 0.5rem 1rem;
+  justify-content: space-around;
+  z-index: 100;
+}
+@media (max-width: 768px) {
+  .bottom-nav { display: flex; }
+}
+.bottom-nav-item {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 0.25rem;
+  background: transparent;
+  border: none;
+  color: var(--color-text-muted);
+  padding: 0.5rem;
+  cursor: pointer;
+  font-size: 0.6875rem;
+}
+.bottom-nav-item.active { color: var(--color-accent); }
+.bottom-nav-item svg { width: 1.5rem; height: 1.5rem; }
+.bottom-nav-item-primary {
+  background: var(--color-accent);
+  color: var(--color-bg);
+  border-radius: 50%;
+  width: 3rem;
+  height: 3rem;
+  margin-top: -1rem;
+  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
+}
+.bottom-nav-item-primary svg { width: 1.75rem; height: 1.75rem; }
+```
+
+---
+
+## 6. Modals
+
+### 6.1 Modal Base
+```html
+<div class="modal-overlay" id="modal-confirm-delete">
+  <div class="modal" role="dialog" aria-modal="true">
+    <div class="modal-header">
+      <h3 class="modal-title">⚠️ Confirm Delete</h3>
+      <button class="btn-ghost modal-close" aria-label="Close">✕</button>
+    </div>
+    <div class="modal-body">
+      <p>Delete "Document Title"?</p>
+    </div>
+    <div class="modal-footer">
+      <button class="btn btn-secondary modal-cancel">Cancel</button>
+      <button class="btn btn-danger modal-confirm">Delete</button>
+    </div>
+  </div>
+</div>
+```
+```css
+.modal-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(0,0,0,0.6);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+  padding: 1rem;
+  opacity: 0;
+  visibility: hidden;
+  transition: opacity 0.2s, visibility 0.2s;
+}
+.modal-overlay.active {
+  opacity: 1;
+  visibility: visible;
+}
+.modal {
+  background: var(--color-surface);
+  border-radius: 12px;
+  width: 100%;
+  max-width: 400px;
+  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
+  transform: scale(0.95);
+  transition: transform 0.2s;
+}
+.modal-overlay.active .modal { transform: scale(1); }
+.modal-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 1rem 1.25rem;
+  border-bottom: 1px solid var(--color-border);
+}
+.modal-title { margin: 0; font-size: 1.125rem; }
+.modal-body { padding: 1.25rem; }
+.modal-footer {
+  display: flex;
+  justify-content: flex-end;
+  gap: 0.75rem;
+  padding: 1rem 1.25rem;
+  border-top: 1px solid var(--color-border);
+}
+```
+
+---
+
+## 7. Feedback
+
+### 7.1 Toast Notification
+```html
+<div class="toast toast-success" role="alert">
+  <span class="toast-icon">✓</span>
+  <span class="toast-message">Document saved</span>
+  <button class="toast-close" aria-label="Dismiss">✕</button>
+</div>
+```
+```css
+.toast {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: 8px;
+  padding: 0.875rem 1rem;
+  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
+  min-width: 280px;
+  max-width: 400px;
+  animation: slideIn 0.2s ease-out;
+}
+@keyframes slideIn {
+  from { transform: translateX(100%); opacity: 0; }
+  to { transform: translateX(0); opacity: 1; }
+}
+.toast-success { border-left: 4px solid var(--color-success); }
+.toast-error { border-left: 4px solid var(--color-danger); }
+.toast-info { border-left: 4px solid var(--color-info); }
+.toast-icon { font-size: 1.125rem; }
+.toast-message { flex: 1; }
+.toast-close {
+  background: transparent;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  padding: 0.25rem;
+}
+.toast-close:hover { color: var(--color-text); }
+```
+
+### 7.2 Loading Spinner
+```html
+<div class="spinner" role="status">
+  <span class="sr-only">Loading...</span>
+</div>
+```
+```css
+.spinner {
+  width: 1.5rem;
+  height: 1.5rem;
+  border: 2px solid var(--color-border);
+  border-top-color: var(--color-accent);
+  border-radius: 50%;
+  animation: spin 0.8s linear infinite;
+}
+@keyframes spin {
+  to { transform: rotate(360deg); }
+}
+.sr-only {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0,0,0,0);
+  border: 0;
+}
+```
+
+### 7.3 Empty State
+```html
+<div class="empty-state">
+  <div class="empty-icon">📄</div>
+  <h3 class="empty-title">No documents yet</h3>
+  <p class="empty-description">Create your first document to get started</p>
+  <button class="btn btn-primary">Create Document</button>
+</div>
+```
+```css
+.empty-state {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  text-align: center;
+  padding: 3rem 1.5rem;
+  gap: 1rem;
+}
+.empty-icon { font-size: 3rem; opacity: 0.5; }
+.empty-title { margin: 0; font-size: 1.25rem; color: var(--color-text); }
+.empty-description { margin: 0; color: var(--color-text-muted); }
+```
+
+### 7.4 Skeleton Loader
+```html
+<div class="skeleton-card">
+  <div class="skeleton skeleton-badge"></div>
+  <div class="skeleton skeleton-title"></div>
+  <div class="skeleton skeleton-tags"></div>
+  <div class="skeleton skeleton-meta"></div>
+</div>
+```
+```css
+.skeleton {
+  background: linear-gradient(
+    90deg,
+    var(--color-border) 25%,
+    var(--color-hover) 50%,
+    var(--color-border) 75%
+  );
+  background-size: 200% 100%;
+  animation: shimmer 1.5s infinite;
+  border-radius: 4px;
+}
+@keyframes shimmer {
+  0% { background-position: 200% 0; }
+  100% { background-position: -200% 0; }
+}
+.skeleton-badge { width: 3rem; height: 1.25rem; }
+.skeleton-title { width: 70%; height: 1.5rem; }
+.skeleton-tags { width: 50%; height: 1.25rem; }
+.skeleton-meta { width: 40%; height: 1rem; }
+```
+
+---
+
+## 8. Layout
+
+### 8.1 App Layout
+```html
+<div class="app-layout">
+  <header class="app-header">...</header>
+  <div class="app-body">
+    <aside class="sidebar">...</aside>
+    <main class="main-content">...</main>
+  </div>
+</div>
+```
+```css
+.app-layout {
+  display: flex;
+  flex-direction: column;
+  height: 100vh;
+  overflow: hidden;
+}
+.app-body {
+  display: flex;
+  flex: 1;
+  overflow: hidden;
+}
+.main-content {
+  flex: 1;
+  overflow-y: auto;
+  padding: 1.5rem;
+  background: var(--color-bg);
+}
+@media (max-width: 768px) {
+  .main-content {
+    padding: 1rem;
+    padding-bottom: 5rem; /* space for bottom nav */
+  }
+}
+```
+
+### 8.2 Toolbar
+```html
+<div class="toolbar">
+  <div class="toolbar-left">
+    <h2 class="toolbar-title">Documents</h2>
+    <span class="toolbar-count">42 documents</span>
+  </div>
+  <div class="toolbar-right">
+    <button class="btn btn-icon-label">
+      <svg><!-- plus icon --></svg>
+      <span>New Doc</span>
+    </button>
+    <button class="btn btn-icon-label">
+      <svg><!-- folder-plus icon --></svg>
+      <span>New Lib</span>
+    </button>
+    <div class="toolbar-divider"></div>
+    <button class="btn-ghost" aria-label="Grid view">⊞</button>
+    <button class="btn-ghost" aria-label="List view">≡</button>
+  </div>
+</div>
+```
+```css
+.toolbar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+  margin-bottom: 1.5rem;
+  flex-wrap: wrap;
+}
+.toolbar-left { display: flex; align-items: baseline; gap: 0.75rem; }
+.toolbar-title { margin: 0; font-size: 1.5rem; font-weight: 600; }
+.toolbar-count { color: var(--color-text-muted); font-size: 0.875rem; }
+.toolbar-right { display: flex; align-items: center; gap: 0.5rem; }
+.toolbar-divider { width: 1px; height: 1.5rem; background: var(--color-border); margin: 0 0.5rem; }
+@media (max-width: 768px) {
+  .toolbar-right .btn span { display: none; }
+}
+```
+
+### 8.3 Split Pane (Editor + Preview)
+```html
+<div class="split-pane">
+  <div class="split-editor">
+    <textarea class="textarea-editor">...</textarea>
+  </div>
+  <div class="split-resize-handle"></div>
+  <div class="split-preview">
+    <!-- Rendered markdown -->
+  </div>
+</div>
+```
+```css
+.split-pane {
+  display: flex;
+  height: 100%;
+  gap: 1px;
+  background: var(--color-border);
+}
+.split-editor,
+.split-preview {
+  flex: 1;
+  overflow-y: auto;
+  background: var(--color-bg);
+}
+.split-resize-handle {
+  width: 4px;
+  background: var(--color-border);
+  cursor: col-resize;
+}
+.split-resize-handle:hover { background: var(--color-accent); }
+@media (max-width: 768px) {
+  .split-pane { flex-direction: column; }
+  .split-resize-handle {
+    width: 100%;
+    height: 4px;
+    cursor: row-resize;
+  }
+}
+```
+
+---
+
+## 9. Form Components
+
+### 9.1 Metadata Panel
+```html
+<aside class="metadata-panel">
+  <div class="meta-section">
+    <h4 class="meta-title">Details</h4>
+    <div class="meta-row">
+      <span class="meta-label">Type</span>
+      <select class="select">...</select>
+    </div>
+    <div class="meta-row">
+      <span class="meta-label">Status</span>
+      <select class="select">...</select>
+    </div>
+    <div class="meta-row">
+      <span class="meta-label">Priority</span>
+      <select class="select">...</select>
+    </div>
+  </div>
+  <div class="meta-section">
+    <h4 class="meta-title">Tags</h4>
+    <div class="tags-input">...</div>
+  </div>
+  <div class="meta-section">
+    <h4 class="meta-title">Timestamps</h4>
+    <div class="meta-row">
+      <span class="meta-label">Created</span>
+      <span class="meta-value">Mar 28, 2026 10:00</span>
+    </div>
+    <div class="meta-row">
+      <span class="meta-label">Updated</span>
+      <span class="meta-value">Mar 28, 2026 12:30</span>
+    </div>
+  </div>
+</aside>
+```
+```css
+.metadata-panel {
+  width: 280px;
+  background: var(--color-surface);
+  border-left: 1px solid var(--color-border);
+  padding: 1rem;
+  overflow-y: auto;
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+}
+.meta-section { display: flex; flex-direction: column; gap: 0.75rem; }
+.meta-title {
+  font-size: 0.75rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+  color: var(--color-text-muted);
+  margin: 0;
+}
+.meta-row {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+.meta-label {
+  font-size: 0.8125rem;
+  color: var(--color-text-muted);
+}
+.meta-value {
+  font-size: 0.875rem;
+  color: var(--color-text);
+}
+@media (max-width: 1024px) {
+  .metadata-panel {
+    width: 100%;
+    border-left: none;
+    border-top: 1px solid var(--color-border);
+  }
+}
+```
+
+---
+
+## 10. Utility Classes
+
+```css
+/* Text utilities */
+.text-muted { color: var(--color-text-muted); }
+.text-accent { color: var(--color-accent); }
+.text-danger { color: var(--color-danger); }
+.text-success { color: var(--color-success); }
+.text-sm { font-size: 0.875rem; }
+.text-xs { font-size: 0.75rem; }
+.font-mono { font-family: var(--font-mono); }
+.font-bold { font-weight: 600; }
+
+/* Spacing */
+.gap-1 { gap: 0.25rem; }
+.gap-2 { gap: 0.5rem; }
+.gap-3 { gap: 0.75rem; }
+.gap-4 { gap: 1rem; }
+.p-2 { padding: 0.5rem; }
+.p-4 { padding: 1rem; }
+.mt-2 { margin-top: 0.5rem; }
+.mt-4 { margin-top: 1rem; }
+.mb-2 { margin-bottom: 0.5rem; }
+.mb-4 { margin-bottom: 1rem; }
+
+/*
\ No newline at end of file
diff --git a/ui/STYLES.md b/ui/STYLES.md
new file mode 100644
index 0000000..72df30b
--- /dev/null
+++ b/ui/STYLES.md
@@ -0,0 +1,1029 @@
+# SimpleNote Web - Style Guide
+
+## 1. Design Tokens
+
+Design tokens are CSS custom properties that define the visual language. They enable theming (dark/light modes) and ensure consistency.
+
+### 1.1 Color Palette
+
+```css
+:root {
+  /* === Dark Theme (Default) === */
+  /* Backgrounds */
+  --color-bg: #0f1117;
+  --color-surface: #1a1d26;
+  --color-surface-raised: #22262f;
+  --color-hover: rgba(255, 255, 255, 0.05);
+  --color-active: rgba(255, 255, 255, 0.08);
+
+  /* Text */
+  --color-text: #e4e6eb;
+  --color-text-secondary: #b0b3b8;
+  --color-text-muted: #65676b;
+
+  /* Borders */
+  --color-border: #303338;
+  --color-border-light: #404249;
+
+  /* Accent (Primary brand color - cyan/teal) */
+  --color-accent: #00d4aa;
+  --color-accent-hover: #00e8bb;
+  --color-accent-alpha: rgba(0, 212, 170, 0.15);
+
+  /* Semantic Colors */
+  --color-success: #31a065;
+  --color-success-bg: rgba(49, 160, 101, 0.15);
+  --color-warning: #cf9d2c;
+  --color-warning-bg: rgba(207, 157, 44, 0.15);
+  --color-danger: #cf4a4a;
+  --color-danger-hover: #e05555;
+  --color-info: #4a90cf;
+  --color-info-bg: rgba(74, 144, 207, 0.15);
+
+  /* Type-specific colors */
+  --color-requirement: #00d4aa;  /* Matches accent */
+  --color-note: #4a90cf;
+  --color-spec: #9b59b6;
+  --color-general: #65676b;
+
+  /* Priority */
+  --color-priority-high: #cf4a4a;
+  --color-priority-medium: #cf9d2c;
+  --color-priority-low: #31a065;
+
+  /* Shadows */
+  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
+  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.25);
+  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.3);
+  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.4);
+
+  /* Focus ring */
+  --focus-ring: 0 0 0 3px rgba(0, 212, 170, 0.4);
+}
+
+/* === Light Theme === */
+[data-theme="light"] {
+  --color-bg: #f5f6f8;
+  --color-surface: #ffffff;
+  --color-surface-raised: #f0f1f3;
+  --color-hover: rgba(0, 0, 0, 0.04);
+  --color-active: rgba(0, 0, 0, 0.06);
+
+  --color-text: #1a1d26;
+  --color-text-secondary: #4a4f5c;
+  --color-text-muted: #8b919d;
+
+  --color-border: #e1e3e8;
+  --color-border-light: #ebedf2;
+
+  --color-accent: #00a884;
+  --color-accent-hover: #00c49a;
+  --color-accent-alpha: rgba(0, 168, 132, 0.12);
+
+  --color-success: #22863a;
+  --color-success-bg: rgba(34, 134, 58, 0.1);
+  --color-warning: #b08800;
+  --color-warning-bg: rgba(176, 136, 0, 0.1);
+  --color-danger: #cb2431;
+  --color-danger-hover: #d93542;
+  --color-info: #0366d6;
+  --color-info-bg: rgba(3, 102, 214, 0.1);
+
+  --color-requirement: #00a884;
+  --color-note: #0366d6;
+  --color-spec: #6f42c1;
+  --color-general: #6a737d;
+
+  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.06);
+  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
+  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.1);
+  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.15);
+
+  --focus-ring: 0 0 0 3px rgba(0, 168, 132, 0.35);
+}
+```
+
+### 1.2 Typography
+
+```css
+:root {
+  /* Font Families */
+  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+  --font-mono: 'JetBrains Mono', 'Fira Code', 'Monaco', 'Consolas', monospace;
+
+  /* Font Sizes (1.25 scale) */
+  --text-xs: 0.64rem;    /* 10.24px */
+  --text-sm: 0.8rem;     /* 12.8px */
+  --text-base: 1rem;     /* 16px */
+  --text-lg: 1.25rem;    /* 20px */
+  --text-xl: 1.563rem;   /* 25px */
+  --text-2xl: 1.953rem;  /* 31.25px */
+  --text-3xl: 2.441rem;  /* 39px */
+
+  /* Line Heights */
+  --leading-tight: 1.25;
+  --leading-normal: 1.5;
+  --leading-relaxed: 1.75;
+
+  /* Font Weights */
+  --font-normal: 400;
+  --font-medium: 500;
+  --font-semibold: 600;
+  --font-bold: 700;
+
+  /* Letter Spacing */
+  --tracking-tight: -0.025em;
+  --tracking-normal: 0;
+  --tracking-wide: 0.025em;
+  --tracking-wider: 0.05em;
+}
+
+/* Google Fonts Import */
+@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');
+```
+
+#### Typography Scale
+
+| Element | Size | Weight | Line Height |
+|---------|------|--------|-------------|
+| H1 | 2rem (32px) | 700 | 1.2 |
+| H2 | 1.5rem (24px) | 600 | 1.25 |
+| H3 | 1.25rem (20px) | 600 | 1.3 |
+| H4 | 1rem (16px) | 600 | 1.4 |
+| Body | 1rem (16px) | 400 | 1.5 |
+| Small | 0.875rem (14px) | 400 | 1.5 |
+| Caption | 0.75rem (12px) | 400 | 1.4 |
+| Code | 0.9375rem (15px) | 400 | 1.6 |
+
+### 1.3 Spacing
+
+```css
+:root {
+  /* Spacing scale (4px base) */
+  --space-0: 0;
+  --space-1: 0.25rem;   /* 4px */
+  --space-2: 0.5rem;    /* 8px */
+  --space-3: 0.75rem;   /* 12px */
+  --space-4: 1rem;      /* 16px */
+  --space-5: 1.25rem;   /* 20px */
+  --space-6: 1.5rem;    /* 24px */
+  --space-8: 2rem;      /* 32px */
+  --space-10: 2.5rem;   /* 40px */
+  --space-12: 3rem;     /* 48px */
+  --space-16: 4rem;     /* 64px */
+  --space-20: 5rem;     /* 80px */
+
+  /* Border Radius */
+  --radius-sm: 4px;
+  --radius-md: 6px;
+  --radius-lg: 8px;
+  --radius-xl: 12px;
+  --radius-2xl: 16px;
+  --radius-full: 9999px;
+
+  /* Transitions */
+  --transition-fast: 0.1s ease;
+  --transition-normal: 0.15s ease;
+  --transition-slow: 0.25s ease;
+  --transition-spring: 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
+}
+```
+
+### 1.4 Z-Index Scale
+
+```css
+:root {
+  --z-base: 0;
+  --z-dropdown: 100;
+  --z-sticky: 200;
+  --z-modal-backdrop: 500;
+  --z-modal: 600;
+  --z-toast: 700;
+  --z-tooltip: 800;
+  --z-max: 9999;
+}
+```
+
+---
+
+## 2. Global Styles
+
+### 2.1 CSS Reset
+
+```css
+*, *::before, *::after {
+  box-sizing: border-box;
+  margin: 0;
+  padding: 0;
+}
+
+html {
+  font-size: 16px;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  text-rendering: optimizeLegibility;
+}
+
+body {
+  font-family: var(--font-sans);
+  font-size: var(--text-base);
+  line-height: var(--leading-normal);
+  color: var(--color-text);
+  background: var(--color-bg);
+  min-height: 100vh;
+}
+
+img, svg {
+  display: block;
+  max-width: 100%;
+}
+
+button {
+  font: inherit;
+  cursor: pointer;
+}
+
+input, textarea, select {
+  font: inherit;
+}
+
+a {
+  color: var(--color-accent);
+  text-decoration: none;
+}
+
+a:hover {
+  text-decoration: underline;
+}
+
+ul, ol {
+  list-style: none;
+}
+
+/* Scrollbar styling */
+::-webkit-scrollbar {
+  width: 8px;
+  height: 8px;
+}
+
+::-webkit-scrollbar-track {
+  background: var(--color-surface);
+}
+
+::-webkit-scrollbar-thumb {
+  background: var(--color-border);
+  border-radius: var(--radius-full);
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: var(--color-text-muted);
+}
+
+/* Selection */
+::selection {
+  background: var(--color-accent-alpha);
+  color: var(--color-text);
+}
+```
+
+### 2.2 Focus Styles
+
+```css
+:focus {
+  outline: none;
+}
+
+:focus-visible {
+  outline: none;
+  box-shadow: var(--focus-ring);
+  border-radius: var(--radius-sm);
+}
+```
+
+### 2.3 Smooth Scrolling
+
+```css
+html {
+  scroll-behavior: smooth;
+}
+
+@media (prefers-reduced-motion: reduce) {
+  html {
+    scroll-behavior: auto;
+  }
+
+  *, *::before, *::after {
+    animation-duration: 0.01ms !important;
+    animation-iteration-count: 1 !important;
+    transition-duration: 0.01ms !important;
+  }
+}
+```
+
+---
+
+## 3. Typography Components
+
+### 3.1 Headings
+
+```css
+h1, .h1 {
+  font-size: var(--text-2xl);
+  font-weight: var(--font-bold);
+  line-height: var(--leading-tight);
+  letter-spacing: var(--tracking-tight);
+  color: var(--color-text);
+}
+
+h2, .h2 {
+  font-size: var(--text-xl);
+  font-weight: var(--font-semibold);
+  line-height: 1.25;
+  letter-spacing: var(--tracking-tight);
+}
+
+h3, .h3 {
+  font-size: var(--text-lg);
+  font-weight: var(--font-semibold);
+  line-height: 1.3;
+}
+
+h4, .h4 {
+  font-size: var(--text-base);
+  font-weight: var(--font-semibold);
+  line-height: 1.4;
+}
+```
+
+### 3.2 Body Text
+
+```css
+p {
+  margin-bottom: var(--space-4);
+}
+
+p:last-child {
+  margin-bottom: 0;
+}
+
+.text-sm {
+  font-size: var(--text-sm);
+}
+
+.text-xs {
+  font-size: var(--text-xs);
+}
+
+.text-muted {
+  color: var(--color-text-muted);
+}
+
+.text-secondary {
+  color: var(--color-text-secondary);
+}
+
+.font-mono {
+  font-family: var(--font-mono);
+}
+```
+
+### 3.3 Prose (Markdown Content)
+
+```css
+.prose {
+  max-width: 70ch;
+  color: var(--color-text);
+}
+
+.prose h1 { /* ... */ }
+.prose h2 { /* ... */ }
+.prose h3 { /* ... */ }
+.prose h4 { /* ... */ }
+
+.prose p {
+  margin-bottom: 1em;
+  line-height: 1.7;
+}
+
+.prose ul,
+.prose ol {
+  margin-bottom: 1em;
+  padding-left: 1.5em;
+}
+
+.prose ul { list-style-type: disc; }
+.prose ol { list-style-type: decimal; }
+
+.prose li {
+  margin-bottom: 0.25em;
+  line-height: 1.6;
+}
+
+.prose code {
+  font-family: var(--font-mono);
+  font-size: 0.875em;
+  background: var(--color-surface);
+  padding: 0.125em 0.375em;
+  border-radius: var(--radius-sm);
+  color: var(--color-accent);
+}
+
+.prose pre {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-lg);
+  padding: 1rem;
+  overflow-x: auto;
+  margin-bottom: 1em;
+}
+
+.prose pre code {
+  background: transparent;
+  padding: 0;
+  color: var(--color-text);
+  font-size: 0.875rem;
+  line-height: 1.6;
+}
+
+.prose blockquote {
+  border-left: 4px solid var(--color-accent);
+  padding-left: 1rem;
+  margin: 1em 0;
+  color: var(--color-text-secondary);
+  font-style: italic;
+}
+
+.prose table {
+  width: 100%;
+  border-collapse: collapse;
+  margin-bottom: 1em;
+}
+
+.prose th,
+.prose td {
+  padding: 0.5rem 0.75rem;
+  border: 1px solid var(--color-border);
+  text-align: left;
+}
+
+.prose th {
+  background: var(--color-surface);
+  font-weight: var(--font-semibold);
+}
+
+.prose tr:hover td {
+  background: var(--color-hover);
+}
+
+/* Task list checkboxes */
+.prose input[type="checkbox"] {
+  margin-right: 0.5em;
+  accent-color: var(--color-accent);
+}
+
+.prose a {
+  color: var(--color-accent);
+  text-decoration: underline;
+}
+
+.prose img {
+  max-width: 100%;
+  border-radius: var(--radius-lg);
+  margin: 1em 0;
+}
+
+.prose hr {
+  border: none;
+  border-top: 1px solid var(--color-border);
+  margin: 2em 0;
+}
+```
+
+---
+
+## 4. Animation Guidelines
+
+### 4.1 Motion Principles
+
+1. **Purposeful**: Animation should communicate state changes, not decorate
+2. **Quick**: Most transitions should be 150-250ms
+3. **Responsive**: Motion should feel immediate to user input
+4. **Respectful**: Don't animate if user prefers reduced motion
+
+### 4.2 Standard Animations
+
+```css
+/* Fade in */
+@keyframes fadeIn {
+  from { opacity: 0; }
+  to { opacity: 1; }
+}
+
+/* Slide in from bottom */
+@keyframes slideInUp {
+  from {
+    opacity: 0;
+    transform: translateY(10px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+/* Slide in from right (toasts) */
+@keyframes slideInRight {
+  from {
+    opacity: 0;
+    transform: translateX(100%);
+  }
+  to {
+    opacity: 1;
+    transform: translateX(0);
+  }
+}
+
+/* Scale in (modals) */
+@keyframes scaleIn {
+  from {
+    opacity: 0;
+    transform: scale(0.95);
+  }
+  to {
+    opacity: 1;
+    transform: scale(1);
+  }
+}
+
+/* Pulse (saving indicator) */
+@keyframes pulse {
+  0%, 100% { opacity: 1; }
+  50% { opacity: 0.5; }
+}
+
+/* Spin (loading) */
+@keyframes spin {
+  to { transform: rotate(360deg); }
+}
+
+/* Shimmer (skeleton) */
+@keyframes shimmer {
+  0% { background-position: 200% 0; }
+  100% { background-position: -200% 0; }
+}
+```
+
+### 4.3 Reduced Motion
+
+```css
+@media (prefers-reduced-motion: reduce) {
+  *,
+  *::before,
+  *::after {
+    animation-duration: 0.01ms !important;
+    animation-iteration-count: 1 !important;
+    transition-duration: 0.01ms !important;
+  }
+}
+```
+
+---
+
+## 5. Responsive Breakpoints
+
+```css
+/* Mobile first breakpoints */
+/* sm: 640px - Large phones */
+/* md: 768px - Tablets */
+/* lg: 1024px - Laptops */
+/* xl: 1280px - Desktops */
+/* 2xl: 1536px - Large screens */
+
+@media (min-width: 640px) {
+  /* sm */
+}
+
+@media (min-width: 768px) {
+  /* md */
+}
+
+@media (min-width: 1024px) {
+  /* lg */
+}
+
+@media (min-width: 1280px) {
+  /* xl */
+}
+
+@media (min-width: 1536px) {
+  /* 2xl */
+}
+
+/* Mobile-only (no breakpoint, mobile first) */
+/* styles apply to all, tablet+ override below */
+
+/* Tablet and up */
+@media (min-width: 768px) {
+  .hide-tablet { display: none; }
+}
+
+/* Desktop only */
+@media (min-width: 1024px) {
+  .hide-desktop { display: none; }
+}
+```
+
+---
+
+## 6. Icon Guidelines
+
+### 6.1 Icon System
+
+Using Lucide Icons (SVG-based, MIT licensed).
+
+```html
+<!-- Size variants -->
+<svg class="icon icon-sm" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <!-- icon path -->
+</svg>
+
+<svg class="icon" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <!-- icon path -->
+</svg>
+
+<svg class="icon icon-lg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <!-- icon path -->
+</svg>
+```
+
+### 6.2 Icon Usage
+
+```css
+.icon {
+  display: inline-block;
+  vertical-align: middle;
+  flex-shrink: 0;
+}
+
+.icon-sm { width: 1rem; height: 1rem; }
+.icon-md { width: 1.25rem; height: 1.25rem; }
+.icon-lg { width: 1.5rem; height: 1.5rem; }
+
+/* Buttons with icons */
+.btn-icon {
+  display: inline-flex;
+  align-items: center;
+  gap: var(--space-2);
+}
+
+/* Icon-only buttons need proper sizing */
+.btn-icon-only {
+  width: 2.5rem;
+  height: 2.5rem;
+  padding: 0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+}
+```
+
+### 6.3 Common Icons
+
+| Icon | Use Case |
+|------|----------|
+| `search` | Search input |
+| `plus` | Create new items |
+| `folder-plus` | Create library |
+| `file-plus` | Create document |
+| `edit` / `pencil` | Edit |
+| `trash-2` | Delete |
+| `download` | Export |
+| `chevron-down` | Dropdown toggle |
+| `chevron-right` | Tree expand |
+| `x` | Close, dismiss |
+| `check` | Confirm, saved |
+| `alert-circle` | Error |
+| `info` | Info toast |
+| `settings` | Settings |
+| `moon` | Dark mode |
+| `sun` | Light mode |
+| `home` | Dashboard |
+| `folder` | Library |
+| `file-text` | Document |
+| `tag` | Tag |
+| `link` | Internal link |
+| `external-link` | External link |
+| `copy` | Copy to clipboard |
+| `eye` | Preview |
+| `eye-off` | Hide |
+| `keyboard` | Shortcuts |
+
+---
+
+## 7. Form Styling
+
+### 7.1 Form Layouts
+
+```css
+/* Vertical form (default) */
+.form-vertical {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-4);
+}
+
+.form-horizontal {
+  display: flex;
+  flex-wrap: wrap;
+  gap: var(--space-4);
+  align-items: flex-start;
+}
+
+.form-horizontal .form-group {
+  flex: 1;
+  min-width: 200px;
+}
+
+/* Inline form */
+.form-inline {
+  display: flex;
+  gap: var(--space-2);
+  align-items: center;
+}
+```
+
+### 7.2 Fieldset & Legend
+
+```css
+fieldset {
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-lg);
+  padding: var(--space-4);
+  margin-bottom: var(--space-4);
+}
+
+legend {
+  font-size: var(--text-sm);
+  font-weight: var(--font-semibold);
+  color: var(--color-text-muted);
+  text-transform: uppercase;
+  letter-spacing: var(--tracking-wider);
+  padding: 0 var(--space-2);
+}
+```
+
+### 7.3 Help Text & Errors
+
+```css
+.help-text {
+  font-size: var(--text-sm);
+  color: var(--color-text-muted);
+  margin-top: var(--space-1);
+}
+
+.error-message {
+  font-size: var(--text-sm);
+  color: var(--color-danger);
+  margin-top: var(--space-1);
+  display: flex;
+  align-items: center;
+  gap: var(--space-1);
+}
+
+.input:invalid,
+.input.error {
+  border-color: var(--color-danger);
+}
+
+.input:invalid:focus,
+.input.error:focus {
+  box-shadow: 0 0 0 3px rgba(207, 74, 74, 0.25);
+}
+```
+
+---
+
+## 8. Status & State Colors
+
+### 8.1 Status Badge Colors
+
+| Status | Background | Text | Border |
+|--------|------------|------|--------|
+| draft | `var(--color-warning-bg)` | `var(--color-warning)` | none |
+| approved | `var(--color-info-bg)` | `var(--color-info)` | none |
+| implemented | `var(--color-success-bg)` | `var(--color-success)` | none |
+
+### 8.2 Priority Colors
+
+| Priority | Color | Emoji |
+|----------|-------|-------|
+| high | `var(--color-priority-high)` | 🔴 |
+| medium | `var(--color-priority-medium)` | 🟡 |
+| low | `var(--color-priority-low)` | 🟢 |
+
+### 8.3 Type Badge Colors
+
+| Type | Border | Text |
+|------|--------|------|
+| requirement | `var(--color-requirement)` | `var(--color-requirement)` |
+| note | `var(--color-note)` | `var(--color-note)` |
+| spec | `var(--color-spec)` | `var(--color-spec)` |
+| general | `var(--color-border)` | `var(--color-text-muted)` |
+
+---
+
+## 9. Loading & Skeleton States
+
+### 9.1 Skeleton Colors
+
+```css
+.skeleton {
+  background: linear-gradient(
+    90deg,
+    var(--color-border) 25%,
+    var(--color-hover) 50%,
+    var(--color-border) 75%
+  );
+  background-size: 200% 100%;
+  animation: shimmer 1.5s infinite;
+}
+
+@keyframes shimmer {
+  0% { background-position: 200% 0; }
+  100% { background-position: -200% 0; }
+}
+
+/* Dark mode adjustment */
+[data-theme="dark"] .skeleton {
+  background: linear-gradient(
+    90deg,
+    var(--color-surface) 25%,
+    var(--color-surface-raised) 50%,
+    var(--color-surface) 75%
+  );
+  background-size: 200% 100%;
+}
+```
+
+### 9.2 Loading Overlay
+
+```css
+.loading-overlay {
+  position: absolute;
+  inset: 0;
+  background: rgba(var(--color-bg), 0.8);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: var(--z-sticky);
+}
+
+[data-theme="dark"] .loading-overlay {
+  background: rgba(15, 17, 23, 0.8);
+}
+```
+
+---
+
+## 10. Dark Mode Implementation
+
+### 10.1 Theme Toggle
+
+```javascript
+// Theme toggle component
+function ThemeToggle() {
+  const toggle = () => {
+    const current = document.documentElement.getAttribute('data-theme');
+    const next = current === 'light' ? 'dark' : 'light';
+    document.documentElement.setAttribute('data-theme', next);
+    localStorage.setItem('theme', next);
+  };
+
+  return `
+    <button class="btn-ghost" onclick="toggleTheme()" aria-label="Toggle theme">
+      ${document.documentElement.getAttribute('data-theme') === 'dark' ? '☀️' : '🌙'}
+    </button>
+  `;
+}
+
+// Initialize theme on load
+function initTheme() {
+  const saved = localStorage.getItem('theme');
+  const preferred = window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
+  const theme = saved || preferred;
+  document.documentElement.setAttribute('data-theme', theme);
+}
+```
+
+### 10.2 CSS Variables at :root vs [data-theme]
+
+```css
+/* Default (dark) - no selector needed */
+:root {
+  --color-bg: #0f1117;
+  /* ... */
+}
+
+/* Light theme - explicit selector */
+[data-theme="light"] {
+  --color-bg: #f5f6f8;
+  /* ... */
+}
+```
+
+---
+
+## 11. Code Syntax Highlighting
+
+Using highlight.js or Prism for code blocks within markdown.
+
+```css
+/* Code highlighting tokens - dark theme */
+.hljs {
+  background: var(--color-surface);
+  color: var(--color-text);
+}
+
+.hljs-keyword { color: #c678dd; }
+.hljs-string { color: #98c379; }
+.hljs-number { color: #d19a66; }
+.hljs-function { color: #61afef; }
+.hljs-comment { color: #5c6370; font-style: italic; }
+.hljs-variable { color: #e06c75; }
+.hljs-attr { color: #d19a66; }
+.hljs-tag { color: #e06c75; }
+.hljs-attribute { color: #d19a66; }
+
+/* Code highlighting - light theme adjustments */
+[data-theme="light"] .hljs-keyword { color: #a626a4; }
+[data-theme="light"] .hljs-string { color: #50a14f; }
+[data-theme="light"] .hljs-number { color: #986801; }
+[data-theme="light"] .hljs-function { color: #4078f2; }
+[data-theme="light"] .hljs-comment { color: #a0a1a7; }
+[data-theme="light"] .hljs-variable { color: #e45649; }
+[data-theme="light"] .hljs-attr { color: #986801; }
+[data-theme="light"] .hljs-tag { color: #e45649; }
+[data-theme="light"] .hljs-attribute { color: #986801; }
+```
+
+---
+
+## 12. Print Styles
+
+```css
+@media print {
+  /* Hide navigation, sidebars, buttons */
+  .sidebar,
+  .app-header,
+  .toolbar,
+  .bottom-nav,
+  .btn,
+  .btn-ghost {
+    display: none !important;
+  }
+
+  /* Expand content */
+  .main-content {
+    width: 100% !important;
+    padding: 0 !important;
+  }
+
+  /* Adjust colors for print */
+  body {
+    background: white;
+    color: black;
+  }
+
+  /* Ensure links show URLs */
+  a[href^="http"]::after {
+    content: " (" attr(href) ")";
+    font-size: 0.8em;
+  }
+
+  /* Avoid page breaks inside elements */
+  .doc-card,
+  .prose h1,
+  .prose h2,
+  .prose h3,
+  .prose table {
+    break-inside: avoid;
+  }
+}
+```
+
+---
+
+## 13. Accessibility Checklist
+
+- [ ] All interactive elements have visible focus indicators
+- [ ] Color contrast ratio ≥ 4.5:1 for text
+- [ ] All images have alt text (or aria-hidden="true")
+- [ ] Form inputs have associated labels
+- [ ] Buttons have accessible names
+- [ ] Icons have aria-label or visible text
+- [ ] Modals trap focus and can be closed with Escape
+- [ ] Toast notifications use role="alert" or role="status"
+- [ ] Loading states announce to screen readers
+- [ ] Reduced motion is respected
+- [ ] Skip-to-content link is provided
+- [ ] Semantic HTML is used (nav, main, aside, article, etc.)
diff --git a/ui/VIEWS.md b/ui/VIEWS.md
new file mode 100644
index 0000000..94eb381
--- /dev/null
+++ b/ui/VIEWS.md
@@ -0,0 +1,541 @@
+# SimpleNote Web - Wireframes
+
+Text-based wireframes for each view. Uses ASCII-style box-drawing to represent layout.
+
+---
+
+## View 1: Dashboard / Main View
+
+### Desktop Layout (>1024px)
+
+```
+┌─────────────────────────────────────────────────────────────────────────────────┐
+│  [≡] SimpleNote          🔍 Search documents...              [🌙] [⚙️] [👤]    │
+├─────────────────┬─────────────────────────────────────────────────────────────┤
+│                 │  Documents                          [+ Doc] [+ Lib] [⊞] [≡]  │
+│  📁 Libraries   ├───────────────────────────────────────────────────────────── │
+│  ├─ Backend     │                                                             │
+│  │  ├─ API      │  ┌──────────────────────────────────────────────────────┐   │
+│  │  └─ Auth     │  │ REQ-001  ·  API Authentication Design                 │   │
+│  ├─ Frontend    │  │ 🏷️ backend  🏷️ api  🏷️ auth                          │   │
+│  └─ DevOps      │  │ 📅 Mar 28  · 👤 agent-001 · ✓ draft · 🔴 high        │   │
+│                 │  └──────────────────────────────────────────────────────┘   │
+│  ─────────────  │  ┌──────────────────────────────────────────────────────┐   │
+│                 │  │ NOTE-002  ·  Deployment Checklist                    │   │
+│  🏷️ Tags        │  │ 🏷️ devops  🏷️ deployment                             │   │
+│  ├─ backend (5) │  │ 📅 Mar 27  · 👤 agent-002 · ✓ approved               │   │
+│  ├─ api (3)     │  └──────────────────────────────────────────────────────┘   │
+│  ├─ auth (2)    │  ┌──────────────────────────────────────────────────────┐   │
+│  ├─ devops (4)  │  │ SPEC-003  ·  Database Schema v2                      │   │
+│  └─ frontend(2) │  │ 🏷️ backend  🏷️ database                              │   │
+│                 │  │ 📅 Mar 26  · 👤 agent-001 · ✓ implemented · 🟡 med   │   │
+│  ─────────────  │  └──────────────────────────────────────────────────────┘   │
+│                 │                                                             │
+│  Quick Links    │  Showing 12 of 42 documents                                 │
+│  ├─ All Docs    │                                                             │
+│  ├─ Recent (7)  │                                                             │
+│  └─ Favorites   │                                                             │
+└─────────────────┴─────────────────────────────────────────────────────────────┘
+```
+
+### Mobile Layout (<768px)
+
+```
+┌─────────────────────────────┐
+│ [≡] SimpleNote    [🔍][🌙]  │
+├─────────────────────────────┤
+│  🔍 Search...               │
+├─────────────────────────────┤
+│                             │
+│  ┌─────────────────────────┐│
+│  │ API Authentication      ││
+│  │ REQ-001 · 🔴 High       ││
+│  │ 🏷️ backend · api        ││
+│  └─────────────────────────┘│
+│  ┌─────────────────────────┐│
+│  │ Deployment Checklist    ││
+│  │ NOTE-002 · ✓ Approved   ││
+│  │ 🏷️ devops               ││
+│  └─────────────────────────┘│
+│  ┌─────────────────────────┐│
+│  │ Database Schema v2      ││
+│  │ SPEC-003 · ✓ Done       ││
+│  │ 🏷️ backend · database   ││
+│  └─────────────────────────┘│
+│                             │
+│  12 of 42 documents         │
+│                             │
+├─────────────────────────────┤
+│  [🏠]  [📁]  [+📝]  [⚙️]    │
+└─────────────────────────────┘
+```
+
+### States
+
+**Loading State**:
+```
+│  ... Loading documents...    │
+│  ████████████░░░░░░░░░  60% │
+```
+
+**Empty State**:
+```
+│                             │
+│       📄                    │
+│    No documents yet         │
+│                             │
+│  Create your first document │
+│      [+ Create Doc]          │
+│                             │
+```
+
+**Search Results**:
+```
+│  🔍 "authentication"        │
+│  Clear ✕                    │
+│  ─────────────────────────  │
+│  3 results for "auth..."   │
+│  ┌─────────────────────────┐│
+│  │ API Authentication      ││
+│  │ ...supports **auth**... ││
+│  └─────────────────────────┘│
+```
+
+---
+
+## View 2: Document Viewer
+
+### Desktop Layout
+
+```
+┌─────────────────────────────────────────────────────────────────────────────────┐
+│  ← Back    API Authentication Design                              [✏️] [↓] [🗑️] │
+├─────────────────────────────────────────────────────────────────────────┬───────┤
+│                                                                         │ Type  │
+│  # API Authentication Design                                           │ REQ   │
+│                                                                         ├───────┤
+│  ## Descripción                                                         │Status │
+│  El sistema debe soportar autenticación via tokens Bearer...           │ draft │
+│                                                                         ├───────┤
+│  ## Criterios de Aceptación                                            │Priority│
+│  - [ ] Endpoint POST /api/v1/auth/token acepta credenciales...         │ 🔴    │
+│  - [ ] Middleware extrae token del header...                          │ High  │
+│  - [ ] Middleware retorna 401 si header ausente...                     ├───────┤
+│  - [ ] Token tiene prefijo `snk_`...                                   │ Tags  │
+│                                                                         │ [backend]│
+│  ## Notas                                                               │ [api]  │
+│  Tokens en esta versión son secretos compartidos...                    │ [auth] │
+│                                                                         │        │
+│  ```javascript                                                         ├───────┤
+│  // authMiddleware.js                                                  │Author │
+│  const token = req.headers.authorization?.replace('Bearer ', '');      │agent- │
+│  ```                                                                    │001    │
+│                                                                         ├───────┤
+│                                                                         │Created│
+│                                                                         │Mar 28 │
+│                                                                         │10:00  │
+│                                                                         ├───────┤
+│                                                                         │Updated│
+│                                                                         │Mar 28 │
+│                                                                         │12:30  │
+└─────────────────────────────────────────────────────────────────────────┴───────┘
+```
+
+### Mobile Layout (Metadata collapses to top)
+
+```
+┌─────────────────────────────────┐
+│ ← Back         [✏️] [↓] [🗑️]  │
+├─────────────────────────────────┤
+│  REQ  ·  draft  ·  🔴 High     │
+│  🏷️ backend  🏷️ api  🏷️ auth  │
+├─────────────────────────────────┤
+│                                 │
+│  # API Authentication Design   │
+│                                 │
+│  ## Descripción                │
+│  El sistema debe soportar...    │
+│                                 │
+│  ## Criterios de Aceptación    │
+│  - [ ] Endpoint POST...        │
+│  - [ ] Middleware extrae...    │
+│                                 │
+│  ## Notas                      │
+│  Tokens en esta versión...      │
+│                                 │
+│  ```javascript                 │
+│  const token = req.headers...  │
+│  ```                           │
+│                                 │
+│  Author: agent-001             │
+│  Created: Mar 28, 2026         │
+└─────────────────────────────────┘
+```
+
+### Delete Confirmation Modal
+
+```
+┌─────────────────────────────────────┐
+│         ⚠️ Confirm Delete           │
+│                                     │
+│  Delete "API Authentication"?      │
+│                                     │
+│  This will permanently remove:     │
+│  • Document content                 │
+│  • All metadata                     │
+│  • Tag associations                 │
+│                                     │
+│  [Cancel]              [Delete]     │
+└─────────────────────────────────────┘
+```
+
+---
+
+## View 3: Document Editor
+
+### Desktop Layout (Split View)
+
+```
+┌─────────────────────────────────────────────────────────────────────────────────┐
+│  Cancel    Editing: API Authentication    [Template ▼]              [Save]    │
+├────────────────────────────────────────────────────────────────┬────────────────┤
+│  Title: [API Authentication Design          ]                   │ Auto-saved ✓  │
+│  Library: [Backend Requirements        ▼]                        │                │
+│  Type: [Requirement ▼]  Status: [Draft ▼]  Priority: [High ▼]  │                │
+├────────────────────────────────────────────────────────────────┤                │
+│  Tags: [+ Add tag...]                                          │                │
+│  [backend ×] [api ×] [auth ×]                                   │                │
+├────────────────────────────────────────────────────────────────┴────────────────┤
+│  [B] [I] [H1] [H2] [H3] [•] [1.] [☐] [</>] [🔗] [📷] [Table]    │ [Preview ▼]  │
+├────────────────────────────────────────────────────────────────┬────────────────┤
+│                                                                 │                │
+│  ## Descripción                                                │  ## Descripción│
+│  El sistema debe soportar autenticación via tokens             │                │
+│  Bearer para todas las rutas protegidas...                     │  ## Criterios  │
+│                                                                 │  de Aceptación │
+│  ## Criterios de Aceptación                                    │                │
+│  - [ ] Endpoint POST /api/v1/auth/token                        │  • [ ] Criterio│
+│  - [ ] Middleware extrae token                                 │    1           │
+│  - [ ] Middleware retorna 401                                  │  • [ ] Criterio│
+│  - [ ] Token tiene prefijo `snk_`                               │    2           │
+│                                                                 │                │
+│  ## Notas                                                       │                │
+│  Tokens en esta versión son secretos compartidos...            │                │
+│                                                                 │                │
+│  ```javascript                                                  │                │
+│  const token = req.headers...                                  │                │
+│  ```                                                            │                │
+│                                                                 │                │
+├────────────────────────────────────────────────────────────────┴────────────────┤
+│  Write                              Preview                                           │
+└─────────────────────────────────────────────────────────────────────────────────┘
+```
+
+### Mobile Layout (Tabbed)
+
+```
+┌─────────────────────────────────┐
+│ [✕]  Edit Document     [Save]  │
+├─────────────────────────────────┤
+│  [Write]  [Preview]  [Meta]    │
+├─────────────────────────────────┤
+│                                 │
+│  Title:                         │
+│  ┌─────────────────────────────┐│
+│  │ API Authentication Design   ││
+│  └─────────────────────────────┘│
+│                                 │
+│  Content:                       │
+│  ┌─────────────────────────────┐│
+│  │ ## Descripción              ││
+│  │ El sistema debe soportar... ││
+│  │                             ││
+│  │ ## Criterios de Aceptación ││
+│  │ - [ ] Endpoint POST...     ││
+│  │                             ││
+│  └─────────────────────────────┘│
+│                                 │
+│  [+] Add tag: [____________]    │
+│  [backend ×] [api ×] [auth ×]  │
+│                                 │
+│  Type: [Requirement ▼]         │
+│  Status: [Draft ▼]             │
+│  Priority: [High ▼]            │
+│  Library: [Backend ▼]          │
+│                                 │
+│  Auto-saved ✓                  │
+└─────────────────────────────────┘
+```
+
+### Template Picker Dropdown
+
+```
+│  [Template ▼]                   │
+│  ┌─────────────────────────────┐│
+│  │ 📋 Requirement Document    ││
+│  │ 📝 General Note             ││
+│  │ 📐 Specification            ││
+│  │ 📄 Blank Document           ││
+│  └─────────────────────────────┘│
+```
+
+### Requirement Template Content (inserted)
+
+```
+---
+id: REQ-XXX
+title: New Requirement
+type: requirement
+priority: medium
+status: draft
+tags: []
+createdBy: user
+createdAt: YYYY-MM-DD
+---
+
+# New Requirement
+
+## Descripción
+[Descripción clara del requerimiento]
+
+## Criterios de Aceptación
+- [ ] Criterio 1
+- [ ] Criterio 2
+
+## Notas
+[Notas adicionales]
+```
+
+### Unsaved Changes Warning Modal
+
+```
+┌─────────────────────────────────────┐
+│         ⚠️ Unsaved Changes          │
+│                                     │
+│  You have unsaved changes.          │
+│                                     │
+│  [Discard]  [Save & Close]          │
+└─────────────────────────────────────┘
+```
+
+---
+
+## View 4: Library Browser
+
+### Desktop Layout
+
+```
+┌─────────────────────────────────────────────────────────────────────────────────┐
+│  Home / Backend / API                                       [+ Doc] [+ Lib]    │
+├─────────────────┬─────────────────────────────────────────────────────────────┤
+│                 │                                                             │
+│  📁 Libraries   │  📁 API                                         3 docs      │
+│  ├─ 🔵 Backend  │  ┌──────────────────────────────────────────────────────┐   │
+│  │  ├─ ⚪ API   │  │ 📄 REST API Endpoints                        REQ-010 │   │
+│  │  └─ ⚪ Auth  │  │     🏷️ api · 🏷️ rest · 📅 Mar 28                   │   │
+│  ├─ 🔵 Frontend│  └──────────────────────────────────────────────────────┘   │
+│  └─ 🔵 DevOps  │  ┌──────────────────────────────────────────────────────┐   │
+│                 │  │ 📄 Authentication Flow                      SPEC-005 │   │
+│  ─────────────  │  │     🏷️ api · 🏷️ auth · 📅 Mar 27                   │   │
+│                 │  └──────────────────────────────────────────────────────┘   │
+│  📁 API         │  ┌──────────────────────────────────────────────────────┐   │
+│  ├─ REST        │  │ 📄 Rate Limiting                       NOTE-012      │   │
+│  └─ GraphQL     │  │     🏷️ api · 📅 Mar 26                              │   │
+│                 │  └──────────────────────────────────────────────────────┘   │
+│  ─────────────  │                                                             │
+│                 │  ─────────────── Sub-libraries ───────────────            │
+│  Quick Links    │  ┌──────────────────────────────────────────────────────┐│
+│  ├─ All Docs    │  │ 📁 REST                              [+ Doc] [+ Lib]  ││
+│  └─ Recent      │  └──────────────────────────────────────────────────────┘│
+│                 │  ┌──────────────────────────────────────────────────────┐│
+│                 │  │ 📁 GraphQL                            [+ Doc] [+ Lib]││
+│                 │  └──────────────────────────────────────────────────────┘│
+└─────────────────┴─────────────────────────────────────────────────────────────┘
+```
+
+### Mobile Layout
+
+```
+┌─────────────────────────────────┐
+│  ← Home / Backend / API        │
+├─────────────────────────────────┤
+│                                 │
+│  📁 API                         │
+│  3 documents · 2 sub-libs       │
+│                                 │
+│  [+] Doc    [+] Lib             │
+│                                 │
+│  ┌─────────────────────────────┐│
+│  │ 📄 REST API Endpoints       ││
+│  │ REQ-010 · 🏷️ api            ││
+│  └─────────────────────────────┘│
+│  ┌─────────────────────────────┐│
+│  │ 📄 Authentication Flow      ││
+│  │ SPEC-005 · 🏷️ api · 🏷️ auth  ││
+│  └─────────────────────────────┘│
+│                                 │
+│  📁 Sub-libraries               │
+│  ├─ 📁 REST                     │
+│  └─ 📁 GraphQL                  │
+│                                 │
+├─────────────────────────────────┤
+│  [🏠]  [📁]  [+📝]  [⚙️]        │
+└─────────────────────────────────┘
+```
+
+### Create Library Modal
+
+```
+┌─────────────────────────────────────┐
+│         📁 New Library             │
+│                                     │
+│  Name:                             │
+│  ┌─────────────────────────────┐  │
+│  │ My New Library               │  │
+│  └─────────────────────────────┘  │
+│                                     │
+│  Parent: [Backend Requirements ▼]  │
+│                                     │
+│  [Cancel]              [Create]    │
+└─────────────────────────────────────┘
+```
+
+### Rename Library Modal
+
+```
+┌─────────────────────────────────────┐
+│         ✏️ Rename Library          │
+│                                     │
+│  Name:                             │
+│  ┌─────────────────────────────┐  │
+│  │ API Requirements            │  │
+│  └─────────────────────────────┘  │
+│                                     │
+│  [Cancel]              [Rename]    │
+└─────────────────────────────────────┘
+```
+
+### Delete Library Modal
+
+```
+┌─────────────────────────────────────┐
+│         ⚠️ Confirm Delete           │
+│                                     │
+│  Delete library "API"?              │
+│                                     │
+│  ⚠️ This will also delete:          │
+│  • 3 documents                      │
+│  • 2 sub-libraries                  │
+│  • 5 total documents                │
+│                                     │
+│  [Cancel]              [Delete]    │
+└─────────────────────────────────────┘
+```
+
+---
+
+## Context Menu (Right-click / Long-press)
+
+```
+│  📄 REST API Endpoints              │
+│  └── [Right-click] →                │
+│                                     │
+│  ┌─────────────────────────┐       │
+│  │ ✏️  Edit                 │       │
+│  │ 📄  Open                 │       │
+│  │ 📋  Duplicate            │       │
+│  │ 📁  Move to Library      │       │
+│  │ ───────────────────────  │       │
+│  │ 🗑️  Delete              │       │
+│  └─────────────────────────┘       │
+```
+
+---
+
+## Toast Notifications
+
+```
+│                                                                  ┌─────────────┐│
+│                                                                  │ ✓ Saved     ││
+│                                                                  └─────────────┘│
+│                                                     ┌─────────────────────┐ │
+│                                                     │ ✕ Failed to save   │ │
+│                                                     │   [Retry]           │ │
+│                                                     └─────────────────────┘ │
+```
+
+---
+
+## Settings Panel
+
+```
+┌─────────────────────────────────────┐
+│         ⚙️ Settings                │
+├─────────────────────────────────────┤
+│                                     │
+│  Appearance                         │
+│  Theme: [Dark ▼] [Light] [System]   │
+│                                     │
+│  ─────────────────────────────────  │
+│                                     │
+│  API Configuration                  │
+│  API URL:                           │
+│  ┌─────────────────────────────────┐│
+│  │ http://localhost:3000/api/v1   ││
+│  └─────────────────────────────────┘│
+│                                     │
+│  API Token:                         │
+│  ┌─────────────────────────────────┐│
+│  │ snk_xxxxxxxxxxxxxxxxxxxxxxxx   ││
+│  └─────────────────────────────────┘│
+│                                     │
+│  [Test Connection]  [Save]          │
+│                                     │
+│  ─────────────────────────────────  │
+│                                     │
+│  Data                               │
+│  [Clear Local Cache]               │
+│                                     │
+│  ─────────────────────────────────  │
+│                                     │
+│  About                              │
+│  SimpleNote Web v0.1.0              │
+│                                     │
+│                              [✕]   │
+└─────────────────────────────────────┘
+```
+
+---
+
+## Keyboard Shortcuts Reference
+
+```
+┌─────────────────────────────────────────────┐
+│  Global                                     │
+├─────────────────────────────────────────────┤
+│  Ctrl/Cmd + K      Focus search             │
+│  Ctrl/Cmd + N      New document             │
+│  Ctrl/Cmd + Shift + N   New library        │
+│  Escape            Close/Clear              │
+├─────────────────────────────────────────────┤
+│  Document Editor                            │
+├─────────────────────────────────────────────┤
+│  Ctrl/Cmd + S      Save                     │
+│  Ctrl/Cmd + B      Bold                     │
+│  Ctrl/Cmd + I      Italic                   │
+│  Ctrl/Cmd + K      Insert link              │
+│  Ctrl/Cmd + Shift + P   Toggle preview      │
+├─────────────────────────────────────────────┤
+│  Document Viewer                            │
+├─────────────────────────────────────────────┤
+│  E                 Edit document             │
+│  X                 Export markdown           │
+│  Delete            Delete (confirm)         │
+├─────────────────────────────────────────────┤
+│  Library Browser                            │
+├─────────────────────────────────────────────┤
+│  R                 Rename                   │
+│  Delete            Delete (confirm)         │
+│  Backspace         Go to parent             │
+└─────────────────────────────────────────────┘
+```