/* CSS Custom Properties (Variables) */
:root {
    /* Light Theme Colors */
    --color-primary: #6366f1;
    --color-primary-hover: #5855eb;
    --color-primary-light: #e0e7ff;
    --color-secondary: #f59e0b;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-info: #3b82f6;

    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --bg-overlay: rgba(0, 0, 0, 0.5);
    --bg-modal: rgba(0, 0, 0, 0.7);

    /* Text Colors */
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-tertiary: #94a3b8;
    --text-inverse: #ffffff;

    /* Border Colors */
    --border-primary: #e2e8f0;
    --border-secondary: #cbd5e1;
    --border-focus: #6366f1;

    /* Shadow Values */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Typography */
    --font-family-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-family-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 400ms ease;

    /* Sidebar */
    --sidebar-width: 280px;
    --header-height: 70px;
}

/* Dark Theme Colors */
[data-theme="dark"] {
    --color-primary: #8b5cf6;
    --color-primary-hover: #7c3aed;
    --color-primary-light: #2d1b69;

    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-overlay: rgba(0, 0, 0, 0.8);

    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;

    --border-primary: #334155;
    --border-secondary: #475569;
}

/* Global Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition-normal), color var(--transition-normal);
    overflow-x: hidden;
}

/* Material Icons Styling */
.material-icons {
    font-family: 'Material Icons';
    font-weight: normal;
    font-style: normal;
    font-size: 24px;
    line-height: 1;
    letter-spacing: normal;
    text-transform: none;
    display: inline-block;
    white-space: nowrap;
    word-wrap: normal;
    direction: ltr;
    -webkit-font-feature-settings: 'liga';
    font-feature-settings: 'liga';
    -webkit-font-smoothing: antialiased;
}

/* Icon size variations */
.material-icons.small { font-size: 18px; }
.material-icons.medium { font-size: 24px; }
.material-icons.large { font-size: 36px; }

/* Loading Screen */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    color: white;
    transition: opacity var(--transition-slow), visibility var(--transition-slow);
}

.loading-screen.hidden {
    opacity: 0;
    visibility: hidden;
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-top: 4px solid white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: var(--spacing-lg);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-screen h2 {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.loading-screen p {
    font-size: var(--font-size-lg);
    opacity: 0.9;
}

/* Main Header */
.main-header {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-primary);
    height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--spacing-xl);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background-color: rgba(var(--bg-primary), 0.95);
}

.header-left {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 700;
    font-size: var(--font-size-xl);
    color: var(--color-primary);
}

.logo-icon {
    font-size: 32px;
}

.main-nav {
    display: flex;
    gap: var(--spacing-sm);
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
    font-size: var(--font-size-sm);
    font-weight: 500;
}

.nav-btn:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.nav-btn.active {
    background-color: var(--color-primary-light);
    color: var(--color-primary);
}

.nav-icon {
    font-size: 18px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

/* Search Container */
.search-container {
    position: relative;
    display: flex;
    align-items: center;
}

.search-icon {
    position: absolute;
    left: var(--spacing-md);
    font-size: 18px;
    color: var(--text-tertiary);
    pointer-events: none;
}

#global-search {
    width: 320px;
    padding: var(--spacing-sm) var(--spacing-md) var(--spacing-sm) 3rem;
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-lg);
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-family: inherit;
    font-size: var(--font-size-sm);
    transition: all var(--transition-fast);
}

#global-search:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.search-results {
    position: absolute;
    top: calc(100% + var(--spacing-sm));
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    max-height: 400px;
    overflow-y: auto;
    z-index: 200;
}

.search-results.hidden {
    display: none;
}

/* Buttons */
.icon-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.icon-btn:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.icon-btn.danger:hover {
    background-color: var(--color-danger);
    color: white;
}

.icon-btn .material-icons {
    font-size: 20px;
}

.primary-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-family: inherit;
    font-size: var(--font-size-sm);
    font-weight: 500;
    transition: all var(--transition-fast);
}

.primary-btn:hover {
    background-color: var(--color-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.secondary-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-family: inherit;
    font-size: var(--font-size-sm);
    font-weight: 500;
    transition: all var(--transition-fast);
}

.secondary-btn:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border-color: var(--border-primary);
}

.btn-icon {
    font-size: 16px;
}

/* Theme Toggle */
#theme-toggle {
    position: relative;
}

.theme-icon {
    font-size: 20px;
    transition: all var(--transition-fast);
}

.theme-icon.hidden {
    opacity: 0;
    transform: scale(0);
}

/* Main Content */
.main-content {
    display: flex;
    min-height: calc(100vh - var(--header-height));
}

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--bg-secondary);
    border-right: 1px solid var(--border-primary);
    padding: var(--spacing-xl);
    overflow-y: auto;
    position: sticky;
    top: var(--header-height);
    height: calc(100vh - var(--header-height));
}

.sidebar-section {
    margin-bottom: var(--spacing-2xl);
}

.sidebar-title {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-md);
}

.quick-actions {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.action-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-family: inherit;
    font-size: var(--font-size-sm);
    transition: all var(--transition-fast);
    width: 100%;
    text-align: left;
}

.action-btn:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border-color: var(--color-primary);
}

.action-btn .material-icons {
    font-size: 16px;
}

.filter-controls {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.filter-select {
    padding: var(--spacing-sm);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: inherit;
    font-size: var(--font-size-sm);
    cursor: pointer;
}

.filter-select:focus {
    outline: none;
    border-color: var(--border-focus);
}

.recent-notes {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.recent-note {
    padding: var(--spacing-sm);
    background-color: var(--bg-primary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.recent-note:hover {
    border-color: var(--color-primary);
    transform: translateY(-1px);
}

.recent-note-title {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.recent-note-date {
    font-size: var(--font-size-xs);
    color: var(--text-tertiary);
}

.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(60px, 1fr));
    gap: var(--spacing-md);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-md);
    background-color: var(--bg-primary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-primary);
}

.stat-number {
    display: block;
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: var(--font-size-xs);
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Content Area */
.content-area {
    flex: 1;
    padding: var(--spacing-xl);
    overflow-y: auto;
}

.view {
    display: none;
}

.view.active {
    display: block;
}

.view-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-primary);
}

.view-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--text-primary);
}

.view-controls {
    display: flex;
    gap: var(--spacing-sm);
}

.view-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 1px solid var(--border-primary);
    background: transparent;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.view-toggle:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.view-toggle.active {
    background-color: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.view-toggle .material-icons {
    font-size: 18px;
}

/* Notes Container */
.notes-container {
    display: grid;
    gap: var(--spacing-lg);
}

.notes-container.list-layout {
    grid-template-columns: 1fr;
}

.notes-container.grid-layout {
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
}

.note-card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.note-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.note-card-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    margin-bottom: var(--spacing-md);
}

.note-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
    line-height: 1.4;
}

.note-actions {
    display: flex;
    gap: var(--spacing-xs);
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.note-card:hover .note-actions {
    opacity: 1;
}

.note-action {
    width: 24px;
    height: 24px;
    border: none;
    background: transparent;
    color: var(--text-tertiary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.note-action:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.note-action.danger:hover {
    background-color: var(--color-danger);
    color: white;
}

.note-action .material-icons {
    font-size: 14px;
}

.note-content {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.note-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.tag {
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--color-primary-light);
    color: var(--color-primary);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 500;
    text-decoration: none;
    transition: all var(--transition-fast);
}

.tag:hover {
    background-color: var(--color-primary);
    color: white;
}

.note-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: var(--font-size-xs);
    color: var(--text-tertiary);
}

.meta-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.btn-icon {
    margin-right: var(--spacing-xs);
    font-size: 18px;
    vertical-align: middle;
}

.meta-item .material-icons {
    font-size: 12px;
}

/* Graph Container */
.graph-container {
    width: 100%;
    height: 600px;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-lg);
    position: relative;
    overflow: hidden;
}

.graph-controls {
    display: flex;
    gap: var(--spacing-sm);
}

/* Tags Container */
.tags-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.tag-group {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-fast);
}

.tag-group:hover {
    border-color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.tag-group-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.tag-group-count {
    font-size: var(--font-size-sm);
    color: var(--text-tertiary);
    margin-bottom: var(--spacing-md);
}

.tag-group-notes {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.tag-group-note {
    padding: var(--spacing-sm);
    background-color: var(--bg-secondary);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    color: var(--text-primary);
    text-decoration: none;
    transition: all var(--transition-fast);
}

.tag-group-note:hover {
    background-color: var(--bg-tertiary);
    transform: translateX(4px);
}

/* Modal Styles */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.modal.hidden {
    opacity: 0;
    visibility: hidden;
}

.modal:not(.hidden) {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background-color: var(--bg-primary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow: hidden;
    transform: scale(0.95);
    transition: transform var(--transition-normal);
}

.modal-content.large {
    max-width: 800px;
}

.modal:not(.hidden) .modal-content {
    transform: scale(1);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-xl);
    border-bottom: 1px solid var(--border-primary);
}

.modal-header h2 {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
}

.detail-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.modal-body {
    padding: var(--spacing-xl);
    overflow-y: auto;
    max-height: calc(90vh - 140px);
}

/* Editor Styles */
.editor-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.title-input {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-family: inherit;
    font-size: var(--font-size-xl);
    font-weight: 600;
    transition: all var(--transition-fast);
}

.title-input:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.content-input {
    width: 100%;
    min-height: 300px;
    padding: var(--spacing-md);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-family: inherit;
    font-size: var(--font-size-base);
    line-height: 1.6;
    resize: vertical;
    transition: all var(--transition-fast);
}

.content-input:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.editor-footer {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.tags-input-container {
    position: relative;
}

.tags-input {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-family: inherit;
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
}

.tags-input:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.suggested-tags {
    position: absolute;
    top: calc(100% + var(--spacing-xs));
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    max-height: 200px;
    overflow-y: auto;
    z-index: 10;
    display: none;
}

.suggested-tags.show {
    display: block;
}

.suggested-tag {
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    border-bottom: 1px solid var(--border-primary);
    transition: background-color var(--transition-fast);
}

.suggested-tag:hover {
    background-color: var(--bg-tertiary);
}

.suggested-tag:last-child {
    border-bottom: none;
}

.editor-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
}

/* Note Detail Styles */
.note-content {
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
    font-size: var(--font-size-base);
    color: var(--text-primary);
}

.linked-notes {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border-primary);
}

.linked-notes h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.linked-note {
    display: block;
    padding: var(--spacing-md);
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    transition: all var(--transition-fast);
}

.linked-note:hover {
    border-color: var(--color-primary);
    transform: translateX(4px);
}

/* Notification */
.notification {
    position: fixed;
    bottom: var(--spacing-xl);
    right: var(--spacing-xl);
    background-color: var(--color-success);
    color: white;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    transform: translateX(400px);
    transition: transform var(--transition-normal);
    z-index: 2000;
}

.notification:not(.hidden) {
    transform: translateX(0);
}

.notification-content {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.notification-icon {
    width: 20px;
    height: 20px;
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.mobile-menu-btn:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.mobile-menu-btn .material-icons {
    font-size: 24px;
}

/* Sidebar Toggle Button */
.sidebar-toggle {
    display: none;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.sidebar-toggle:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.sidebar-toggle .material-icons {
    font-size: 20px;
}

/* Mobile Navigation Overlay */
.mobile-nav-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-modal);
    z-index: 1000;
    display: flex;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.mobile-nav-overlay:not(.hidden) {
    opacity: 1;
    visibility: visible;
}

.mobile-nav-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-lg) var(--spacing-xl);
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-primary);
}

.mobile-nav {
    flex: 1;
    padding: var(--spacing-xl);
    background-color: var(--bg-primary);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.mobile-nav-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-lg) var(--spacing-xl);
    border: none;
    background: transparent;
    color: var(--text-secondary);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
    font-size: var(--font-size-lg);
    font-weight: 500;
    text-align: left;
    width: 100%;
}

.mobile-nav-btn:hover,
.mobile-nav-btn.active {
    background-color: var(--color-primary-light);
    color: var(--color-primary);
}

.mobile-nav-btn .nav-icon {
    font-size: 24px;
}

.mobile-nav-actions {
    padding: var(--spacing-xl);
    background-color: var(--bg-primary);
    border-top: 1px solid var(--border-primary);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .sidebar {
        width: 260px;
    }
    
    #global-search {
        width: 280px;
    }
    
    .notes-container.grid-layout {
        grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    }
}

@media (max-width: 1024px) {
    :root {
        --sidebar-width: 240px;
    }
    
    .sidebar-toggle {
        display: flex;
    }
    
    .sidebar {
        width: var(--sidebar-width);
    }
    
    #global-search {
        width: 240px;
    }
    
    .notes-container.grid-layout {
        grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    }
    
    .modal-content {
        width: 90%;
        max-width: 600px;
    }
}

@media (max-width: 768px) {
    .main-header {
        padding: 0 var(--spacing-md);
        position: relative;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .header-left {
        gap: var(--spacing-md);
    }
    
    .main-nav {
        display: none;
    }
    
    #global-search {
        width: 180px;
        font-size: var(--font-size-sm);
    }
    
    .sidebar {
        position: fixed;
        left: -100%;
        top: 0;
        width: 280px;
        height: 100vh;
        z-index: 900;
        transition: left var(--transition-normal);
        box-shadow: var(--shadow-xl);
    }
    
    .sidebar.open {
        left: 0;
    }
    
    .sidebar-overlay {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: var(--bg-modal);
        z-index: 800;
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
    }
    
    .sidebar-overlay.show {
        opacity: 1;
        visibility: visible;
    }
    
    .content-area {
        width: 100%;
        padding: var(--spacing-md);
        margin-left: 0;
    }
    
    .main-content {
        flex-direction: column;
    }
    
    .notes-container.grid-layout {
        grid-template-columns: 1fr;
    }
    
    .note-card {
        padding: var(--spacing-md);
    }
    
    .view-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-md);
    }
    
    .view-controls {
        width: 100%;
        justify-content: flex-end;
    }
    
    .modal-content {
        width: 95%;
        margin: var(--spacing-md);
        max-height: calc(100vh - 2rem);
        overflow-y: auto;
    }
    
    .modal-body {
        padding: var(--spacing-md);
    }
    
    .editor-actions {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .editor-actions .primary-btn,
    .editor-actions .secondary-btn {
        width: 100%;
        justify-content: center;
    }
    
    .note-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-sm);
    }
    
    .tags-container {
        grid-template-columns: 1fr;
    }
    
    .graph-container {
        height: 400px;
    }
    
    /* Touch-friendly improvements */
    .icon-btn {
        width: 44px;
        height: 44px;
        -webkit-tap-highlight-color: transparent;
    }
    
    .note-action {
        width: 32px;
        height: 32px;
        -webkit-tap-highlight-color: transparent;
    }
    
    .primary-btn,
    .secondary-btn {
        padding: var(--spacing-md) var(--spacing-lg);
        font-size: var(--font-size-base);
        -webkit-tap-highlight-color: transparent;
    }
    
    .action-btn {
        padding: var(--spacing-md);
        font-size: var(--font-size-base);
        -webkit-tap-highlight-color: transparent;
    }
    
    .nav-btn,
    .mobile-nav-btn {
        -webkit-tap-highlight-color: transparent;
    }
    
    .note-card {
        -webkit-tap-highlight-color: transparent;
    }
    
    /* Improve scrolling on iOS */
    .sidebar,
    .content-area,
    .modal-body {
        -webkit-overflow-scrolling: touch;
    }
}

@media (max-width: 480px) {
    .main-header {
        padding: 0 var(--spacing-sm);
    }
    
    .header-left {
        gap: var(--spacing-sm);
    }
    
    .logo-text {
        display: none;
    }
    
    #global-search {
        width: 140px;
        padding: var(--spacing-xs) var(--spacing-sm) var(--spacing-xs) 2.5rem;
    }
    
    .search-icon {
        left: var(--spacing-sm);
        font-size: 16px;
    }
    
    .view-title {
        font-size: var(--font-size-2xl);
    }
    
    .stats {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--spacing-sm);
    }
    
    .stat-item {
        padding: var(--spacing-sm);
    }
    
    .content-area {
        padding: var(--spacing-sm);
    }
    
    .sidebar {
        width: 100%;
        left: -100%;
    }
    
    .note-card {
        padding: var(--spacing-sm);
    }
    
    .note-card-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-sm);
    }
    
    .note-actions {
        align-self: flex-end;
        opacity: 1;
    }
    
    .modal-content {
        width: 100%;
        height: 100%;
        margin: 0;
        border-radius: 0;
        max-height: 100vh;
    }
    
    .title-input,
    .content-input,
    .tags-input {
        font-size: 16px; /* Prevents zoom on iOS */
    }
    
    .content-input {
        min-height: 200px;
    }
    
    /* Notification positioning for mobile */
    .notification {
        bottom: var(--spacing-md);
        right: var(--spacing-md);
        left: var(--spacing-md);
        width: auto;
        text-align: center;
    }
}

/* Landscape orientation optimizations */
@media (max-width: 768px) and (orientation: landscape) {
    .sidebar {
        width: 60%;
        max-width: 300px;
    }
    
    .modal-content {
        max-height: 90vh;
    }
    
    .content-input {
        min-height: 150px;
    }
}

/* Very small screens */
@media (max-width: 320px) {
    .main-header {
        padding: 0 var(--spacing-xs);
    }
    
    .header-left {
        gap: var(--spacing-xs);
    }
    
    #global-search {
        width: 120px;
    }
    
    .content-area {
        padding: var(--spacing-xs);
    }
    
    .note-card {
        padding: var(--spacing-xs);
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus States for Accessibility */
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Print Styles */
@media print {
    .sidebar,
    .main-header,
    .modal {
        display: none !important;
    }
    
    .content-area {
        width: 100% !important;
        padding: 0 !important;
    }
    
    .note-card {
        break-inside: avoid;
        margin-bottom: var(--spacing-lg);
    }
}