/* === CSS RESET AND BASE STYLES === */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* === CSS VARIABLES FOR THEMES === */
:root {
    /* Light theme colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;
    --accent-primary: #3b82f6;
    --accent-hover: #2563eb;
    --accent-light: #eff6ff;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --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);
}

[data-theme="dark"] {
    /* Dark theme colors */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --border-light: #475569;
    --accent-primary: #3b82f6;
    --accent-hover: #60a5fa;
    --accent-light: #1e3a8a;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
}

/* === BASE TYPOGRAPHY AND LAYOUT === */
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 14px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: all 0.3s ease;
    overflow-x: hidden;
}

.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* === HEADER === */
.app-header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.app-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.app-title i {
    color: var(--accent-primary);
    font-size: 1.75rem;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    padding: 0.75rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    transform: translateY(-1px);
}

/* === MAIN CONTENT === */
.main-content {
    flex: 1;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    width: 100%;
}

/* === SEARCH === */
.search-container {
    margin-bottom: 2rem;
}

.search-box {
    position: relative;
    max-width: 400px;
    margin: 0 auto;
}

.search-box i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    z-index: 1;
}

.search-box input {
    width: 100%;
    padding: 1rem 1rem 1rem 3rem;
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 0.95rem;
    transition: all 0.2s ease;
}

.search-box input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-light);
}

.search-box input::placeholder {
    color: var(--text-muted);
}

/* === NOTES GRID === */
.notes-container {
    position: relative;
}

.notes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.note-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 1.5rem;
    cursor: pointer;
    transition: all 0.2s ease;
    position: relative;
    overflow: hidden;
}

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

.note-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
}

.note-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
    line-height: 1.4;
}

.note-date {
    font-size: 0.8rem;
    color: var(--text-muted);
    white-space: nowrap;
}

.note-preview {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 4;
    -webkit-box-orient: vertical;
    overflow: hidden;
    margin-bottom: 1rem;
}

.note-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.note-tag {
    background: var(--accent-light);
    color: var(--accent-primary);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

/* === EMPTY STATE === */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-muted);
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: 1.5rem;
    opacity: 0.5;
}

.empty-state h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.empty-state p {
    font-size: 1rem;
}

/* === MODAL === */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--bg-primary);
    border-radius: 1.5rem;
    box-shadow: var(--shadow-xl);
    width: 100%;
    max-width: 900px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    transform: scale(0.9) translateY(20px);
    transition: all 0.3s ease;
}

.modal-overlay.active .modal-content {
    transform: scale(1) translateY(0);
}

.modal-header {
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.note-title-input {
    flex: 1;
    border: none;
    background: transparent;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    outline: none;
}

.note-title-input::placeholder {
    color: var(--text-muted);
}

.modal-actions {
    display: flex;
    gap: 0.5rem;
}

.btn-icon {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    padding: 0.75rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

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

.modal-body {
    flex: 1;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.editor-container {
    height: 100%;
    display: flex;
    flex-direction: column;
}

.editor-tabs {
    display: flex;
    border-bottom: 1px solid var(--border-color);
}

.tab-btn {
    background: transparent;
    border: none;
    padding: 1rem 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.9rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.tab-btn.active {
    color: var(--accent-primary);
    border-bottom: 2px solid var(--accent-primary);
}

.tab-btn:hover:not(.active) {
    color: var(--text-primary);
    background: var(--bg-tertiary);
}

.editor-content {
    flex: 1;
    position: relative;
    overflow: hidden;
}

#noteContent {
    width: 100%;
    height: 400px;
    border: none;
    background: transparent;
    color: var(--text-primary);
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    padding: 2rem;
    resize: none;
    outline: none;
}

#noteContent::placeholder {
    color: var(--text-muted);
}

.note-preview {
    width: 100%;
    height: 400px;
    padding: 2rem;
    overflow-y: auto;
    display: none;
    background: var(--bg-secondary);
}

.note-preview.active {
    display: block;
}

.note-preview h1,
.note-preview h2,
.note-preview h3,
.note-preview h4,
.note-preview h5,
.note-preview h6 {
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.note-preview h1 { font-size: 1.75rem; }
.note-preview h2 { font-size: 1.5rem; }
.note-preview h3 { font-size: 1.25rem; }

.note-preview p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.note-preview code {
    background: var(--bg-tertiary);
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.85rem;
}

.note-preview pre {
    background: var(--bg-tertiary);
    padding: 1rem;
    border-radius: 0.5rem;
    overflow-x: auto;
    margin: 1rem 0;
}

.note-preview blockquote {
    border-left: 4px solid var(--accent-primary);
    padding-left: 1rem;
    margin: 1rem 0;
    color: var(--text-muted);
    font-style: italic;
}

.note-preview ul,
.note-preview ol {
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

.note-preview li {
    margin-bottom: 0.25rem;
}

.internal-link {
    color: var(--accent-primary);
    text-decoration: none;
    background: var(--accent-light);
    padding: 0.125rem 0.375rem;
    border-radius: 0.25rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.internal-link:hover {
    background: var(--accent-primary);
    color: white;
}

.modal-footer {
    padding: 1.5rem 2rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.note-info {
    display: flex;
    gap: 1.5rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.btn-primary {
    background: var(--accent-primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.75rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
}

/* === FLOATING ACTION BUTTON === */
.fab {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 3.5rem;
    height: 3.5rem;
    border-radius: 50%;
    background: var(--accent-primary);
    color: white;
    border: none;
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    z-index: 999;
}

.fab:hover {
    background: var(--accent-hover);
    transform: scale(1.1) translateY(-2px);
    box-shadow: var(--shadow-xl);
}

/* === RESPONSIVE DESIGN === */

/* Tablet */
@media (max-width: 768px) {
    .header-content {
        padding: 0 1rem;
    }
    
    .main-content {
        padding: 1.5rem 1rem;
    }
    
    .notes-grid {
        grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
        gap: 1rem;
    }
    
    .modal-content {
        margin: 0.5rem;
        max-height: 95vh;
    }
    
    .modal-header,
    .modal-footer {
        padding: 1rem 1.5rem;
    }
    
    #noteContent,
    .note-preview {
        height: 300px;
        padding: 1.5rem;
    }
    
    .fab {
        bottom: 1.5rem;
        right: 1.5rem;
        width: 3rem;
        height: 3rem;
    }
}

/* Mobile */
@media (max-width: 480px) {
    .app-title {
        font-size: 1.25rem;
    }
    
    .app-title i {
        font-size: 1.5rem;
    }
    
    .main-content {
        padding: 1rem;
    }
    
    .notes-grid {
        grid-template-columns: 1fr;
    }
    
    .search-box {
        max-width: none;
    }
    
    .modal-overlay {
        padding: 0.5rem;
    }
    
    .modal-content {
        border-radius: 1rem;
    }
    
    .modal-header {
        flex-direction: column;
        align-items: stretch;
        gap: 1rem;
    }
    
    .modal-actions {
        align-self: flex-end;
    }
    
    .note-title-input {
        font-size: 1.1rem;
    }
    
    .editor-tabs {
        flex-wrap: wrap;
    }
    
    .tab-btn {
        flex: 1;
        min-width: 50%;
        justify-content: center;
    }
    
    #noteContent,
    .note-preview {
        height: 250px;
        padding: 1rem;
        font-size: 0.85rem;
    }
    
    .modal-footer {
        flex-direction: column;
        gap: 1rem;
        align-items: stretch;
    }
    
    .note-info {
        justify-content: space-between;
    }
    
    .fab {
        bottom: 1rem;
        right: 1rem;
        width: 2.5rem;
        height: 2.5rem;
        font-size: 1rem;
    }
}

/* === SCROLLBAR STYLING === */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* === ANIMATIONS === */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.note-card {
    animation: fadeIn 0.3s ease-out;
}

/* === FOCUS AND ACCESSIBILITY === */
button:focus,
input:focus,
textarea:focus {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}