:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --text-color: #1f2937;
    --text-secondary: #4b5563;
    --bg-color: #f3f4f6;
    --sidebar-bg: #ffffff;
    --card-bg: #ffffff;
    --border-color: #e5e7eb;
    --code-bg: #1e293b;
    --code-text: #e2e8f0;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --expert-color: #7c3aed;
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --primary-color: #60a5fa;
    --primary-hover: #93c5fd;
    --text-color: #f3f4f6;
    --text-secondary: #9ca3af;
    --bg-color: #0f172a;
    --sidebar-bg: #1e293b;
    --card-bg: #1e293b;
    --border-color: #334155;
    --code-bg: #020617;
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.5);
    --shadow-md: 0 10px 15px -3px rgb(0 0 0 / 0.5);
    --shadow-lg: 0 20px 25px -5px rgb(0 0 0 / 0.5);
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

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

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

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

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    color: var(--text-color);
    background-color: var(--bg-color);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

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

/* Sidebar */
.sidebar {
    width: 280px;
    background-color: var(--sidebar-bg);
    border-inline-end: 1px solid var(--border-color);
    position: fixed;
    top: 0;
    bottom: 0;
    inset-inline-start: 0;
    height: 100vh;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    z-index: 10;
    transition: background-color 0.3s, border-color 0.3s;
}

.logo {
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo h1 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

.version {
    font-size: 0.75rem;
    color: var(--text-secondary);
    background: var(--bg-color);
    padding: 0.1rem 0.4rem;
    border-radius: 4px;
    border: 1px solid var(--border-color);
}

/* Theme & Lang Toggle */
.theme-toggle-container {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    margin-bottom: 1rem;
    gap: 0.5rem;
}

.lang-toggle {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 600;
    padding: 0.4rem 0.8rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: var(--transition);
    font-family: 'Inter', sans-serif;
}

.lang-toggle:hover {
    background-color: var(--bg-color);
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.theme-toggle:hover {
    background-color: var(--bg-color);
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.sun-icon { display: none; }
.moon-icon { display: block; }

[data-theme="dark"] .sun-icon { display: block; }
[data-theme="dark"] .moon-icon { display: none; }

/* Navigation Styles */
.nav-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.nav-group {
    margin-bottom: 1.5rem;
}

.nav-group-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.8rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    opacity: 0.8;
}

.nav-group-title i {
    color: var(--primary-color);
    font-size: 0.9rem;
}

.nav-sublist {
    list-style: none;
    padding-inline-start: 0.5rem; /* Indent sub-items */
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--text-secondary);
    padding: 0.6rem 1rem;
    border-radius: 8px;
    font-size: 0.9rem;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    margin-bottom: 0.2rem;
    border: 1px solid transparent;
}

.nav-item i {
    width: 1.2rem; /* Fixed width for alignment */
    text-align: center;
    font-size: 0.9rem;
    opacity: 0.7;
    transition: opacity 0.2s;
}

.nav-item:hover {
    background-color: var(--bg-color);
    color: var(--primary-color);
    border-color: var(--border-color);
    transform: translateX(4px);
}

.nav-item:hover i {
    opacity: 1;
    color: var(--primary-color);
}

.nav-item.active {
    background: linear-gradient(90deg, rgba(37, 99, 235, 0.1), transparent);
    color: var(--primary-color);
    font-weight: 600;
    border-color: rgba(37, 99, 235, 0.2);
}

.nav-item.active i {
    opacity: 1;
}

[data-theme="dark"] .nav-item.active {
    background: linear-gradient(90deg, rgba(96, 165, 250, 0.15), transparent);
    border-color: rgba(96, 165, 250, 0.2);
}

/* RTL Support */
[dir="rtl"] .nav-item:hover {
    transform: translateX(-4px);
}

.sidebar-footer {
    margin-top: auto;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.github-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-color);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

.github-link:hover {
    color: var(--primary-color);
}

/* Main Content */
.content {
    margin-inline-start: 280px;
    flex: 1;
    padding: 3rem 4rem;
    max-width: 1200px;
}

section {
    margin-bottom: 5rem;
    scroll-margin-top: 2rem;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero {
    margin-bottom: 2rem;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--text-color);
    line-height: 1.2;
    background: linear-gradient(135deg, var(--primary-color), var(--expert-color));
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    max-width: 800px;
}

.badges {
    display: flex;
    gap: 0.75rem;
}

.badge {
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 500;
}

.badge.flutter { background-color: rgba(2, 132, 199, 0.1); color: #0284c7; }
.badge.dart { background-color: rgba(22, 163, 74, 0.1); color: #16a34a; }
[data-theme="dark"] .badge.flutter { color: #38bdf8; }
[data-theme="dark"] .badge.dart { color: #4ade80; }

.badge.warning { background-color: rgba(217, 119, 6, 0.1); color: #d97706; }
.badge.success { background-color: rgba(5, 150, 105, 0.1); color: #059669; }
[data-theme="dark"] .badge.warning { color: #fbbf24; }
[data-theme="dark"] .badge.success { color: #34d399; }

/* Cards */
.card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
    border-color: var(--primary-color);
}

.info-card {
    border-inline-start: 4px solid var(--primary-color);
    background: linear-gradient(to right, rgba(37, 99, 235, 0.05), transparent);
}

.analogy-card {
    border-inline-start: 4px solid var(--expert-color);
    background: linear-gradient(to right, rgba(124, 58, 237, 0.05), transparent);
    margin-top: 1rem;
}

.analogy-card h3 {
    color: var(--expert-color);
    font-size: 1.1rem;
}

.analogy-card p {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.section-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.complexity-badge {
    font-size: 0.75rem;
    padding: 0.2rem 0.6rem;
    border-radius: 4px;
    font-weight: 600;
    text-transform: uppercase;
}

.complexity-badge.easy { background: rgba(5, 150, 105, 0.1); color: #059669; }
.complexity-badge.medium { background: rgba(217, 119, 6, 0.1); color: #d97706; }
.complexity-badge.hard { background: rgba(220, 38, 38, 0.1); color: #dc2626; }
.complexity-badge.expert { background: rgba(124, 58, 237, 0.1); color: #7c3aed; }

[data-theme="dark"] .complexity-badge.easy { color: #34d399; }
[data-theme="dark"] .complexity-badge.medium { color: #fbbf24; }
[data-theme="dark"] .complexity-badge.hard { color: #f87171; }
[data-theme="dark"] .complexity-badge.expert { color: #a78bfa; }

h2 {
    font-size: 2rem;
    color: var(--text-color);
}

h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: var(--text-color);
}

ul {
    list-style-position: inside;
    margin-inline-start: 0.5rem;
}

.structure-list li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.structure-list strong {
    color: var(--text-color);
}

/* Lists */
.check-list, .stat-list {
    list-style: none;
    margin: 0;
}

.check-list li {
    position: relative;
    padding-inline-start: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.check-list li::before {
    content: "✓";
    position: absolute;
    inset-inline-start: 0;
    color: var(--success-color);
    font-weight: bold;
}

.stat-list li {
    display: flex;
    justify-content: space-between;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.stat-list li:last-child {
    border-bottom: none;
}

.note {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 1rem;
    font-style: italic;
}

/* Code Blocks */
.code-block {
    background: #1e1e1e; /* VS Code dark theme background */
    border-radius: 8px;
    overflow: hidden;
    margin-top: 1.5rem;
    border: 1px solid #333;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
    direction: ltr;
}

/* Override Highlight.js background to match our container */
.hljs {
    background: transparent !important;
    padding: 0 !important; /* We handle padding in pre */
}

.code-header {
    background: #252526; /* VS Code title bar color */
    color: #cccccc;
    padding: 0.5rem 1rem;
    font-size: 0.85rem;
    font-family: 'Inter', sans-serif;
    border-bottom: 1px solid #333;
    display: flex;
    align-items: center;
    justify-content: space-between; /* Ensure button goes to right */
}

.code-header-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.code-header-title::before {
    content: "";
    display: block;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: #ff5f56;
    box-shadow: 20px 0 0 #ffbd2e, 40px 0 0 #27c93f;
    margin-inline-end: 3rem; /* Space after dots */
}

.copy-btn {
    background: transparent;
    border: 1px solid rgba(255,255,255,0.1);
    color: #858585;
    padding: 0.3rem 0.8rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.75rem;
    font-family: 'Inter', sans-serif;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.copy-btn:hover {
    background: rgba(255,255,255,0.1);
    color: #fff;
    border-color: rgba(255,255,255,0.3);
}

.copy-btn.copied {
    border-color: var(--success-color);
    color: var(--success-color);
}

pre {
    padding: 1.5rem;
    overflow-x: auto;
    margin: 0;
    background: #1e1e1e;
}

code {
    font-family: 'JetBrains Mono', monospace;
    color: #d4d4d4; /* VS Code default text color */
    font-size: 0.9rem;
    line-height: 1.5;
}

/* Mermaid Diagrams */
.mermaid {
    display: flex;
    justify-content: center;
    margin: 2rem 0;
    background: var(--card-bg);
    padding: 1rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

/* Comparison Table */
.comparison-table-container {
    overflow-x: auto;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    margin-top: 1.5rem;
    box-shadow: var(--shadow-sm);
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--card-bg);
}

.comparison-table th,
.comparison-table td {
    padding: 1rem;
    text-align: start;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-secondary);
}

.comparison-table th {
    background: var(--bg-color);
    font-weight: 600;
    color: var(--text-color);
}

.comparison-table tr:last-child td {
    border-bottom: none;
}

.comparison-table tr:nth-child(even) {
    background-color: rgba(0, 0, 0, 0.02);
}

[data-theme="dark"] .comparison-table tr:nth-child(even) {
    background-color: rgba(255, 255, 255, 0.02);
}

.comparison-table tr:hover {
    background-color: rgba(37, 99, 235, 0.05);
}

/* Decision Cards */
.decision-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 1.5rem;
}

.decision-card h3 {
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid;
}

.decision-card.bloc h3 { border-color: var(--primary-color); color: var(--primary-color); }
.decision-card.getx h3 { border-color: var(--expert-color); color: var(--expert-color); }

.decision-card ul {
    list-style: none;
    margin: 0;
}

.decision-card li {
    margin-bottom: 0.75rem;
    padding-inline-start: 1.5rem;
    position: relative;
    color: var(--text-secondary);
}

.decision-card li::before {
    content: "•";
    position: absolute;
    inset-inline-start: 0;
    font-weight: bold;
    color: var(--text-color);
}

/* Accordion */
.accordion {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.accordion-item {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
}

.accordion-header {
    padding: 1rem 1.5rem;
    cursor: pointer;
    font-weight: 600;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    transition: background-color 0.2s;
}

.accordion-header:hover {
    background-color: var(--bg-color);
}

.accordion-header::after {
    content: '+';
    font-size: 1.25rem;
    font-weight: 400;
    transition: transform 0.3s;
}

.accordion-item.active .accordion-header::after {
    transform: rotate(45deg);
}

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    padding: 0 1.5rem;
    background: var(--bg-color);
}

.accordion-item.active .accordion-content {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
}

/* Resource Cards */
.resource-card ul {
    list-style: none;
    margin: 0;
}

.resource-card li {
    margin-bottom: 0.5rem;
}

.resource-card a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.resource-card a:hover {
    text-decoration: underline;
}

footer {
    margin-top: 4rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    inset-inline-end: 2rem;
    background: var(--primary-color);
    color: white;
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 50;
    border: none;
    font-size: 1.2rem;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--primary-hover);
    transform: translateY(-4px);
}

/* Mobile Header & Overlay (Hidden on Desktop) */
.mobile-header {
    display: none;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: var(--sidebar-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 50;
}

.mobile-logo {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--primary-color);
}

#mobile-menu-btn {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.25rem;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 90;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s;
    backdrop-filter: blur(2px);
}

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

/* Topic Organization */
.topic-group {
    margin-bottom: 3rem;
    padding-inline-start: 1.5rem;
    border-inline-start: 2px solid var(--border-color);
}

.topic-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.3rem;
    margin-bottom: 1.5rem;
    color: var(--text-color);
    font-weight: 600;
}

.topic-title i {
    color: var(--primary-color);
    opacity: 0.8;
    font-size: 1.1rem;
}

/* Adjust existing elements within topic groups */
.topic-group .mermaid {
    margin: 1.5rem 0;
}

.topic-group h4 {
    margin-top: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-weight: 600;
}

/* Responsive */
@media (max-width: 768px) {
    .mobile-header {
        display: flex;
    }

    .app-container {
        flex-direction: column;
    }

    .sidebar {
        position: fixed;
        top: 0;
        bottom: 0;
        left: 0; /* Default LTR */
        width: 280px;
        transform: translateX(-100%);
        z-index: 100;
        transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        box-shadow: var(--shadow-lg);
        border-right: 1px solid var(--border-color);
    }

    /* RTL Support for Sidebar */
    [dir="rtl"] .sidebar {
        left: auto;
        right: 0;
        transform: translateX(100%);
        border-right: none;
        border-left: 1px solid var(--border-color);
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .content {
        margin-inline-start: 0;
        padding: 1.5rem;
    }

    .hero h1 {
        font-size: 2rem;
    }
}