:root {
    /* Dark Theme Colors */
    --primary-bg: #0a0a0a;
    --secondary-bg: #1a1a1a;
    --tertiary-bg: #2a2a2a;
    --card-bg: #151515;
    --border-color: #333;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --text-muted: #888;
    --accent-primary: #00ff88;
    --accent-secondary: #0088ff;
    --accent-tertiary: #ff0088;
    --accent-warning: #ffaa00;
    --accent-error: #ff4444;
    --hover-bg: rgba(0, 255, 136, 0.1);
    --neon-glow: 0 0 10px rgba(0, 255, 136, 0.3);
    --neon-glow-strong: 0 0 20px rgba(0, 255, 136, 0.6);
    
    /* Fonts */
    --font-primary: 'Orbitron', monospace;
    --font-code: 'Roboto Mono', monospace;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Light Theme Colors */
[data-theme="light"] {
    --primary-bg: #ffffff;
    --secondary-bg: #f8f9fa;
    --tertiary-bg: #e9ecef;
    --card-bg: #ffffff;
    --border-color: #dee2e6;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #adb5bd;
    --accent-primary: #007bff;
    --accent-secondary: #6f42c1;
    --accent-tertiary: #e83e8c;
    --accent-warning: #ffc107;
    --accent-error: #dc3545;
    --hover-bg: rgba(0, 123, 255, 0.1);
    --neon-glow: 0 0 10px rgba(0, 123, 255, 0.3);
    --neon-glow-strong: 0 0 20px rgba(0, 123, 255, 0.6);
}

/* Light theme specific adjustments */
[data-theme="light"] .intro-card {
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

[data-theme="light"] .intro-card:hover {
    box-shadow: 0 4px 20px rgba(0, 123, 255, 0.2);
}

[data-theme="light"] .card-icon {
    box-shadow: 0 2px 10px rgba(0, 123, 255, 0.3);
}

[data-theme="light"] .example-item,
[data-theme="light"] .complexity-row {
    border: 1px solid var(--border-color);
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

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

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

::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: var(--radius-sm);
}

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

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(26, 26, 26, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    padding: var(--spacing-md) 0;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 900;
    font-size: 1.5rem;
    color: var(--accent-primary);
    text-shadow: var(--neon-glow);
}

.logo i {
    font-size: 2rem;
}

/* Search Container */
.search-container {
    position: relative;
    flex: 1;
    max-width: 400px;
    margin: 0 var(--spacing-lg);
}

.search-input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    padding-left: 2.5rem;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    color: var(--text-primary);
    font-family: var(--font-code);
    transition: all var(--transition-fast);
}

.search-input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: var(--neon-glow);
}

.search-icon {
    position: absolute;
    left: var(--spacing-sm);
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

/* Header Controls */
.header-controls {
    display: flex;
    gap: var(--spacing-sm);
}

.control-btn {
    padding: var(--spacing-sm);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 40px;
    height: 40px;
}

.control-btn:hover {
    background: var(--hover-bg);
    border-color: var(--accent-primary);
    box-shadow: var(--neon-glow);
    transform: translateY(-2px);
}

/* Main Container */
.main-container {
    display: flex;
    margin-top: 80px;
    min-height: calc(100vh - 80px);
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--secondary-bg);
    border-right: 1px solid var(--border-color);
    padding: var(--spacing-lg);
    transition: transform var(--transition-normal);
    position: sticky;
    top: 80px;
    height: calc(100vh - 80px);
    overflow-y: auto;
}

.sidebar.collapsed {
    transform: translateX(-240px);
}

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

.sidebar-header h3 {
    color: var(--accent-primary);
    font-weight: 700;
    text-shadow: var(--neon-glow);
}

.sidebar-toggle {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

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

/* Category Navigation */
.category-nav {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.category-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
}

.category-item:hover {
    background: var(--hover-bg);
    transform: translateX(4px);
}

.category-item.active {
    background: var(--hover-bg);
    border-left: 3px solid var(--accent-primary);
    box-shadow: var(--neon-glow);
}

.category-item i {
    font-size: 1.2rem;
    color: var(--accent-primary);
    min-width: 20px;
}

.category-item span:first-of-type {
    flex: 1;
    font-weight: 500;
}

.category-item .count {
    background: var(--accent-primary);
    color: var(--primary-bg);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

/* Main Content */
.main-content {
    flex: 1;
    padding: var(--spacing-lg);
    max-width: calc(100vw - 280px);
}

/* DSA Introduction Section */
#dsaIntro {
    max-width: 1200px;
    margin: 0 auto;
}

.intro-header {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.intro-header h1 {
    font-size: 3rem;
    font-weight: 900;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-md);
}

.intro-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.intro-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xxl);
}

.intro-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.intro-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
}

.intro-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--neon-glow-strong);
    border-color: var(--accent-primary);
}

.card-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.card-icon i {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.intro-card h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.intro-card p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.6;
}

.dsa-examples, .complexity-examples, .space-examples {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.example-item {
    background: var(--tertiary-bg);
    padding: var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    color: var(--text-secondary);
}

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

.complexity-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--tertiary-bg);
    padding: var(--spacing-sm);
    border-radius: var(--spacing-sm);
}

.complexity-name {
    font-family: var(--font-code);
    font-weight: bold;
    color: var(--accent-primary);
    min-width: 60px;
}

.complexity-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.intro-actions {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xxl);
}

.btn {
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-md);
    font-family: var(--font-primary);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    color: var(--text-primary);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--neon-glow-strong);
}

.btn-secondary {
    background: var(--tertiary-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

/* Responsive Design for DSA Intro */
@media (max-width: 768px) {
    .intro-header h1 {
        font-size: 2rem;
    }
    
    .intro-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
    
    .intro-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .complexity-row {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-xs);
    }
    
    .header-left {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-md);
    }
}

/* Content Sections */
.content-section {
    display: none;
}

.content-section.active {
    display: block;
}

/* Section Header */
.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
}

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

.header-left h2 {
    margin: 0;
}

.section-header h2 {
    font-size: 2rem;
    color: var(--accent-primary);
    text-shadow: var(--neon-glow);
}

/* View Controls */
.view-controls {
    display: flex;
    gap: var(--spacing-xs);
}

.view-btn {
    padding: var(--spacing-sm);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-muted);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.view-btn.active,
.view-btn:hover {
    background: var(--hover-bg);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

/* Problems Grid */
.problems-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

.problems-grid.list-view {
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
}

.problems-grid.list-view .problem-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    min-height: 80px;
}

.problems-grid.list-view .problem-card .problem-header {
    flex: 1;
    margin-bottom: 0;
    margin-right: var(--spacing-lg);
}

.problems-grid.list-view .problem-card .problem-meta {
    margin-bottom: 0;
}

.problems-grid.list-view .problem-card .problem-description {
    display: none;
}

.problems-grid.list-view .problem-card .problem-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.problems-grid.list-view .problem-card .problem-number {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--accent-primary);
    margin-right: var(--spacing-md);
    min-width: 40px;
}

.problems-grid.list-view .problem-card:hover {
    transform: translateX(4px);
    background: var(--tertiary-bg);
}

.problems-grid.list-view .problem-card .problem-title {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xs);
}

.problems-grid.list-view .problem-card .problem-category {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.problems-grid.list-view .problem-card .problem-status {
    font-size: 0.8rem;
    padding: 2px 8px;
    border-radius: var(--radius-sm);
    background: var(--secondary-bg);
    border: 1px solid var(--border-color);
}

/* Submit Problem Modal Styles */
.submit-modal {
    max-width: 800px;
    max-height: 90vh;
    overflow-y: auto;
}

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

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

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
}

.form-group label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.form-group input,
.form-group select,
.form-group textarea {
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--secondary-bg);
    color: var(--text-primary);
    font-family: var(--font-code);
    font-size: 0.9rem;
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: var(--neon-glow);
}

.form-group textarea {
    min-height: 100px;
    resize: vertical;
}

.form-group textarea[name="constraints"] {
    min-height: 80px;
}

.form-group textarea[name="examples"] {
    min-height: 120px;
}

.form-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
    margin-top: var(--spacing-lg);
}

.btn {
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: var(--font-primary);
}

.btn-primary {
    background: var(--accent-primary);
    color: var(--primary-bg);
}

.btn-primary:hover {
    background: var(--accent-secondary);
    transform: translateY(-2px);
    box-shadow: var(--neon-glow-strong);
}

.btn-secondary {
    background: var(--tertiary-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

/* Success/Error Messages */
.message {
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

.message.success {
    background: rgba(0, 255, 0, 0.1);
    color: #00ff00;
    border: 1px solid rgba(0, 255, 0, 0.3);
}

.message.error {
    background: rgba(255, 0, 0, 0.1);
    color: var(--accent-error);
    border: 1px solid rgba(255, 0, 0, 0.3);
}

/* Admin Panel Styles */
.admin-modal {
    max-width: 1000px;
    max-height: 90vh;
    overflow-y: auto;
}

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

.admin-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: var(--secondary-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

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

.submissions-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    max-height: 400px;
    overflow-y: auto;
}

.submission-item {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    transition: all var(--transition-fast);
}

.submission-item:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--neon-glow);
}

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

.submission-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.submission-meta {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.submission-category,
.submission-difficulty,
.submission-status {
    padding: 2px 8px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.submission-category {
    background: rgba(0, 136, 255, 0.2);
    color: var(--accent-secondary);
}

.submission-difficulty.easy {
    background: rgba(0, 255, 0, 0.2);
    color: #00ff00;
}

.submission-difficulty.medium {
    background: rgba(255, 170, 0, 0.2);
    color: var(--accent-warning);
}

.submission-difficulty.hard {
    background: rgba(255, 68, 68, 0.2);
    color: var(--accent-error);
}

.submission-status.pending {
    background: rgba(255, 170, 0, 0.2);
    color: var(--accent-warning);
}

.submission-status.approved {
    background: rgba(0, 255, 0, 0.2);
    color: #00ff00;
}

.submission-status.rejected {
    background: rgba(255, 68, 68, 0.2);
    color: var(--accent-error);
}

.submission-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
    margin-bottom: var(--spacing-md);
}

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

.submission-actions .btn {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.8rem;
}

.submission-user {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: var(--spacing-sm);
}

.submission-date {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: var(--spacing-xs);
}

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

.problem-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.problem-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--neon-glow-strong);
    border-color: var(--accent-primary);
}

.problem-card:hover::before {
    transform: scaleX(1);
}

.problem-card.solved {
    border-color: var(--accent-primary);
}

.problem-card.solved .problem-status {
    color: var(--accent-primary);
}

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

.problem-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.problem-status {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.problem-meta {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.difficulty {
    padding: 2px 8px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.difficulty.easy {
    background: rgba(0, 255, 0, 0.2);
    color: #00ff00;
}

.difficulty.medium {
    background: rgba(255, 170, 0, 0.2);
    color: var(--accent-warning);
}

.difficulty.hard {
    background: rgba(255, 68, 68, 0.2);
    color: var(--accent-error);
}

.category-tag {
    background: rgba(0, 136, 255, 0.2);
    color: var(--accent-secondary);
    padding: 2px 8px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 500;
}

.problem-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
}

/* Problem Detail View */
.problem-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
}

.back-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: var(--font-primary);
}

.back-btn:hover {
    background: var(--hover-bg);
    border-color: var(--accent-primary);
    transform: translateX(-2px);
}

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

/* Language Toggle */
.language-toggle {
    display: flex;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.lang-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: var(--font-primary);
    font-weight: 500;
}

.lang-btn.active {
    background: var(--accent-primary);
    color: var(--primary-bg);
}

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

/* Problem Content */
.problem-content {
    max-width: none;
}

#problemTitle {
    font-size: 2.5rem;
    color: var(--accent-primary);
    text-shadow: var(--neon-glow);
    margin-bottom: var(--spacing-md);
}

.problem-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.statement, .constraints {
    background: var(--card-bg);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    margin-bottom: var(--spacing-md);
}

.statement h3, .constraints h3 {
    color: var(--accent-secondary);
    margin-bottom: var(--spacing-md);
}

/* Tabs */
.tabs {
    display: flex;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.tab-btn {
    padding: var(--spacing-md) var(--spacing-lg);
    background: transparent;
    border: none;
    border-bottom: 2px solid transparent;
    color: var(--text-muted);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: var(--font-primary);
    font-weight: 500;
    position: relative;
}

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

.tab-btn.active {
    color: var(--accent-primary);
    border-bottom-color: var(--accent-primary);
    text-shadow: var(--neon-glow);
}

/* Tab Content */
.tab-content {
    margin-top: var(--spacing-lg);
}

.tab-panel {
    display: none;
}

.tab-panel.active {
    display: block;
}

/* Code Container */
.code-container {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.code-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md);
    background: var(--tertiary-bg);
    border-bottom: 1px solid var(--border-color);
}

.code-title {
    font-weight: 600;
    color: var(--accent-primary);
}

.code-controls {
    display: flex;
    gap: var(--spacing-xs);
}

.code-block {
    font-family: var(--font-code);
    font-size: 0.9rem;
    line-height: 1.6;
    padding: var(--spacing-lg);
    margin: 0;
    overflow-x: auto;
    color: var(--text-primary);
}

.code-content {
    margin: 0;
    padding: var(--spacing-md);
    white-space: pre-wrap;
    word-wrap: break-word;
    overflow-x: auto;
    background: var(--card-bg);
    color: var(--text-primary);
    font-family: var(--font-code);
    font-size: 0.9rem;
    line-height: 1.5;
}

/* Animation Controls */
.animation-controls {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-md);
}

.anim-btn {
    padding: var(--spacing-sm);
    background: var(--tertiary-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
    min-width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.anim-btn:hover {
    background: var(--hover-bg);
    border-color: var(--accent-primary);
}

.play-btn:hover {
    color: var(--accent-primary);
}

.pause-btn:hover {
    color: var(--accent-warning);
}

.reset-btn:hover {
    color: var(--accent-error);
}

.speed-control {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-left: auto;
}

.speed-control label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

#speedSlider {
    width: 100px;
}

#speedValue {
    color: var(--accent-primary);
    font-weight: 600;
    min-width: 30px;
}

/* Animation Canvas */
.animation-canvas {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    min-height: 400px;
    padding: var(--spacing-lg);
    position: relative;
    overflow: hidden;
}

/* Variable Tracker */
.variable-tracker {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.variable-tracker h4 {
    color: var(--accent-secondary);
    margin-bottom: var(--spacing-md);
}

.variables-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: var(--spacing-sm);
}

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

.variable-name {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 2px;
}

.variable-value {
    font-weight: 600;
    color: var(--accent-primary);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    z-index: 2000;
    backdrop-filter: blur(5px);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--secondary-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xxl);
    max-width: 600px;
    width: 90%;
    max-height: 80%;
    overflow-y: auto;
    position: relative;
}

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

.modal-header h3 {
    color: var(--accent-primary);
    text-shadow: var(--neon-glow);
}

.close-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 1.2rem;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.close-btn:hover {
    color: var(--accent-error);
    background: rgba(255, 68, 68, 0.1);
}

/* Progress Stats */
.progress-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

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

.stat-value {
    font-size: 2rem;
    font-weight: 900;
    color: var(--accent-primary);
    text-shadow: var(--neon-glow);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: var(--spacing-xs);
}

/* Loading Spinner */
.loading-spinner {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 10, 10, 0.9);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 3000;
    backdrop-filter: blur(10px);
}

.spinner {
    width: 50px;
    height: 50px;
    border: 3px solid var(--border-color);
    border-top: 3px solid var(--accent-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.loading-text {
    color: var(--text-secondary);
    margin-top: var(--spacing-md);
    font-family: var(--font-code);
}

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

/* Responsive Design */
@media (max-width: 1024px) {
    .main-container {
        flex-direction: column;
    }
    
    .sidebar {
        position: fixed;
        top: 80px;
        left: 0;
        height: calc(100vh - 80px);
        z-index: 1500;
        transform: translateX(-100%);
        transition: transform var(--transition-normal);
    }
    
    .sidebar.active {
        transform: translateX(0);
    }
    
    .main-content {
        max-width: 100%;
        padding: var(--spacing-md);
    }
    
    .problems-grid {
        grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
        gap: var(--spacing-md);
    }
}

@media (max-width: 768px) {
    .header-content {
        padding: 0 var(--spacing-md);
    }
    
    .search-container {
        margin: 0 var(--spacing-sm);
        max-width: 200px;
    }
    
    .logo span {
        display: none;
    }
    
    .problems-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-sm);
    }
    
    .problem-card {
        padding: var(--spacing-md);
    }
    
    #problemTitle {
        font-size: 1.8rem;
    }
    
    .tabs {
        overflow-x: auto;
        scrollbar-width: none;
        -ms-overflow-style: none;
    }
    
    .tabs::-webkit-scrollbar {
        display: none;
    }
    
    .tab-btn {
        white-space: nowrap;
        flex-shrink: 0;
    }
    
    .modal-content {
        padding: var(--spacing-lg);
        width: 95%;
    }
    
    .progress-stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .header-content {
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }
    
    .search-container {
        order: 3;
        flex-basis: 100%;
        max-width: none;
        margin: var(--spacing-sm) 0 0 0;
    }
    
    .animation-controls {
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }
    
    .speed-control {
        margin-left: 0;
        flex-basis: 100%;
    }
}

/* Print Styles */
@media print {
    .sidebar,
    .header,
    .animation-controls,
    .modal {
        display: none !important;
    }
    
    .main-content {
        max-width: 100%;
        margin: 0;
        padding: 0;
    }
    
    .code-block {
        background: white;
        color: black;
        border: 1px solid #ccc;
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --primary-bg: #000000;
        --secondary-bg: #111111;
        --text-primary: #ffffff;
        --accent-primary: #00ff00;
        --border-color: #444444;
    }
}

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