/* ================================================
   GauxVocs - Artistic Design System
   ================================================ */

/* CSS Variables */
:root {
    /* Primary Colors - Vibrant Gradient Palette */
    --primary-start: #667eea;
    --primary-end: #764ba2;
    --primary-color: #667eea;
    --primary-hover: #5a67d8;

    /* Accent Colors */
    --accent-pink: #f093fb;
    --accent-orange: #f5576c;
    --accent-cyan: #4facfe;
    --accent-green: #00f2fe;

    /* Status Colors */
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;

    /* Background & Surface */
    --bg-dark: #0f0f23;
    --bg-color: #1a1a2e;
    --bg-surface: #16213e;
    --card-bg: rgba(255, 255, 255, 0.05);
    --glass-bg: rgba(255, 255, 255, 0.08);
    --glass-border: rgba(255, 255, 255, 0.1);

    /* Text Colors */
    --text-color: #ffffff;
    --text-secondary: #a0aec0;
    --text-muted: #718096;

    /* Difficulty Colors */
    --beginner-color: #10b981;
    --beginner-bg: rgba(16, 185, 129, 0.15);
    --intermediate-color: #f59e0b;
    --intermediate-bg: rgba(245, 158, 11, 0.15);
    --advanced-color: #ef4444;
    --advanced-bg: rgba(239, 68, 68, 0.15);

    /* Shadows & Effects */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 30px rgba(102, 126, 234, 0.3);
    --shadow-glow-pink: 0 0 30px rgba(240, 147, 251, 0.3);

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--primary-start), var(--primary-end));
    --gradient-accent: linear-gradient(135deg, var(--accent-pink), var(--accent-orange));
    --gradient-cool: linear-gradient(135deg, var(--accent-cyan), var(--accent-green));
}

/* ================================================
   Reset & Base Styles
   ================================================ */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-dark);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: 'Space Grotesk', sans-serif;
    font-weight: 700;
    line-height: 1.2;
}

a {
    color: inherit;
    text-decoration: none;
}

/* ================================================
   Animated Background
   ================================================ */

.animated-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
    background: var(--bg-dark);
}

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.5;
    animation: float 20s ease-in-out infinite;
}

.orb-1 {
    width: 600px;
    height: 600px;
    background: var(--gradient-primary);
    top: -200px;
    right: -200px;
    animation-delay: 0s;
}

.orb-2 {
    width: 500px;
    height: 500px;
    background: var(--gradient-accent);
    bottom: -150px;
    left: -150px;
    animation-delay: -7s;
}

.orb-3 {
    width: 400px;
    height: 400px;
    background: var(--gradient-cool);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation-delay: -14s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(50px, -50px) scale(1.1); }
    50% { transform: translate(-30px, 30px) scale(0.95); }
    75% { transform: translate(-50px, -30px) scale(1.05); }
}

/* ================================================
   Container
   ================================================ */

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* ================================================
   Glass Card Effect
   ================================================ */

.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
}

/* ================================================
   Navbar
   ================================================ */

.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 0.625rem 0;
    background: rgba(15, 15, 35, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-wrapper {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}

.logo {
    font-size: 1.5rem;
    position: relative;
    z-index: 1;
    animation: pulse-glow 3s ease-in-out infinite;
}

.logo-glow {
    position: absolute;
    width: 40px;
    height: 40px;
    background: var(--gradient-primary);
    border-radius: 50%;
    filter: blur(12px);
    opacity: 0.5;
}

@keyframes pulse-glow {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.brand-text {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-color);
}

.brand-accent {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.navbar-links {
    display: flex;
    gap: 0.5rem;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.4rem 0.875rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
    font-size: 0.875rem;
    color: var(--text-secondary);
    transition: var(--transition);
    border: 1px solid transparent;
}

.nav-link:hover {
    color: var(--text-color);
    background: var(--glass-bg);
    border-color: var(--glass-border);
}

.nav-link.active {
    color: var(--text-color);
    background: var(--gradient-primary);
    border-color: transparent;
    box-shadow: var(--shadow-glow);
}

.nav-icon {
    font-size: 1.1rem;
}

/* ================================================
   Main Content
   ================================================ */

.main-content {
    flex: 1;
    padding: 1.5rem 0;
}

/* ================================================
   Footer
   ================================================ */

.footer {
    padding: 0.75rem 0;
    background: rgba(15, 15, 35, 0.6);
    border-top: 1px solid var(--glass-border);
}

.footer-content {
    text-align: center;
}

.footer-text {
    color: var(--text-muted);
    font-size: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.footer-icon {
    opacity: 0.5;
    font-size: 0.7rem;
}

.footer-decoration {
    display: none;
}

.footer-decoration span {
    width: 4px;
    height: 4px;
    border-radius: 50%;
    background: var(--gradient-primary);
    opacity: 0.5;
}

/* ================================================
   Hero Section
   ================================================ */

.hero {
    text-align: center;
    padding: 4rem 0;
    position: relative;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1.25rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 999px;
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    animation: fade-in-up 0.6s ease-out;
}

.badge-icon {
    animation: bounce 2s ease-in-out infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-5px); }
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 4.5rem);
    margin-bottom: 1.5rem;
    animation: fade-in-up 0.6s ease-out 0.1s backwards;
}

.title-line {
    display: block;
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 2rem;
    animation: fade-in-up 0.6s ease-out 0.2s backwards;
}

.hero-stats {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2rem;
    margin-bottom: 2.5rem;
    animation: fade-in-up 0.6s ease-out 0.3s backwards;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-family: 'Space Grotesk', sans-serif;
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-divider {
    width: 1px;
    height: 40px;
    background: var(--glass-border);
}

.hero-cta {
    animation: fade-in-up 0.6s ease-out 0.4s backwards;
}

@keyframes fade-in-up {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ================================================
   Buttons
   ================================================ */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    border: none;
    border-radius: var(--radius-md);
    font-family: 'Space Grotesk', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
}

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

.btn-secondary:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.12);
    border-color: rgba(255, 255, 255, 0.2);
}

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
}

.btn-ghost:hover {
    color: var(--text-color);
}

.btn-large {
    padding: 1.1rem 2.5rem;
    font-size: 1.125rem;
}

.btn-glow {
    animation: glow-pulse 2s ease-in-out infinite;
}

@keyframes glow-pulse {
    0%, 100% { box-shadow: var(--shadow-md), 0 0 20px rgba(102, 126, 234, 0.3); }
    50% { box-shadow: var(--shadow-md), 0 0 40px rgba(102, 126, 234, 0.5); }
}

.btn-arrow {
    transition: transform var(--transition);
}

.btn:hover .btn-arrow {
    transform: translateX(4px);
}

/* ================================================
   Features Showcase
   ================================================ */

.features-showcase {
    margin: 4rem 0;
}

.feature-main {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    padding: 3rem;
    align-items: center;
}

.feature-visual {
    display: flex;
    justify-content: center;
    perspective: 1000px;
}

.card-preview {
    position: relative;
    width: 280px;
    height: 180px;
    animation: card-float 6s ease-in-out infinite;
}

@keyframes card-float {
    0%, 100% { transform: translateY(0) rotateY(-5deg); }
    50% { transform: translateY(-15px) rotateY(5deg); }
}

.preview-front,
.preview-back {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    box-shadow: var(--shadow-lg);
}

.preview-front {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    z-index: 2;
}

.preview-back {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    transform: translateX(30px) translateY(20px) rotateY(10deg);
    z-index: 1;
}

.preview-word,
.preview-translation {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 1.75rem;
    font-weight: 700;
    color: white;
}

.preview-hint {
    font-size: 1.5rem;
}

.feature-info {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.feature-tag {
    display: inline-block;
    width: fit-content;
    padding: 0.375rem 0.875rem;
    background: var(--gradient-primary);
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.feature-info h2 {
    font-size: 2rem;
}

.feature-info p {
    color: var(--text-secondary);
    line-height: 1.7;
}

.feature-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin: 0.5rem 0;
}

.feature-list li {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-secondary);
}

.check-icon {
    color: var(--success-color);
    font-weight: 700;
}

/* ================================================
   Section Headers
   ================================================ */

.section-header {
    text-align: center;
    margin-bottom: 2.5rem;
}

.section-tag {
    display: inline-block;
    padding: 0.375rem 0.875rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.section-header h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--text-muted);
}

/* ================================================
   Categories Section
   ================================================ */

.categories-section {
    margin: 5rem 0;
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 1rem;
}

.category-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
    padding: 1.5rem 1rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.category-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--card-color);
    opacity: 0;
    transition: var(--transition);
}

.category-card:hover {
    transform: translateY(-4px);
    border-color: var(--card-color);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.category-card:hover::before {
    opacity: 1;
}

.category-icon-wrapper {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
}

.category-icon {
    font-size: 1.75rem;
}

.category-card h3 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-color);
}

.category-arrow {
    position: absolute;
    bottom: 0.75rem;
    right: 0.75rem;
    opacity: 0;
    transform: translateX(-5px);
    transition: var(--transition);
    color: var(--card-color);
}

.category-card:hover .category-arrow {
    opacity: 1;
    transform: translateX(0);
}

/* ================================================
   Difficulty Section
   ================================================ */

.difficulty-section {
    margin: 5rem 0;
}

.difficulty-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    max-width: 900px;
    margin: 0 auto;
}

.difficulty-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 2.5rem 2rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    transition: var(--transition);
    cursor: pointer;
    text-align: center;
}

.difficulty-card:hover {
    transform: translateY(-6px);
}

.difficulty-card.difficulty-beginner:hover {
    border-color: var(--beginner-color);
    box-shadow: 0 10px 40px rgba(16, 185, 129, 0.2);
}

.difficulty-card.difficulty-intermediate:hover {
    border-color: var(--intermediate-color);
    box-shadow: 0 10px 40px rgba(245, 158, 11, 0.2);
}

.difficulty-card.difficulty-advanced:hover {
    border-color: var(--advanced-color);
    box-shadow: 0 10px 40px rgba(239, 68, 68, 0.2);
}

.difficulty-icon {
    font-size: 3rem;
}

.difficulty-card h3 {
    font-size: 1.25rem;
}

.difficulty-card p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* ================================================
   Page Header
   ================================================ */

.page-header {
    text-align: center;
    margin-bottom: 1rem;
}

.page-title-wrapper {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 0.25rem;
}

.page-icon {
    font-size: 1.75rem;
}

.page-header h1 {
    font-size: 1.75rem;
}

.page-description {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* ================================================
   Flashcard Layout with Sidebar
   ================================================ */

.flashcard-layout {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 1.5rem;
    align-items: start;
    min-height: calc(100vh - 120px);
}

.filters-sidebar {
    padding: 1rem;
    position: sticky;
    top: 70px;
    max-height: calc(100vh - 100px);
    overflow-y: auto;
}

.sidebar-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--glass-border);
}

.sidebar-icon {
    font-size: 1.25rem;
}

.sidebar-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
}

.filter-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.filter-section {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.filter-label {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.filter-icon {
    font-size: 0.8rem;
}

.filter-options {
    display: flex;
    flex-wrap: wrap;
    gap: 0.375rem;
}

.filter-chip {
    padding: 0.3rem 0.6rem;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    font-size: 0.7rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.filter-chip:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-color);
}

.filter-chip.active {
    background: var(--gradient-primary);
    border-color: transparent;
    color: white;
}

.filter-chip.filter-beginner.active {
    background: var(--beginner-color);
}

.filter-chip.filter-intermediate.active {
    background: var(--intermediate-color);
}

.filter-chip.filter-advanced.active {
    background: var(--advanced-color);
}

.btn-clear-sidebar {
    margin-top: 0.5rem;
    font-size: 0.75rem;
    width: 100%;
    justify-content: center;
    padding: 0.4rem;
}

.flashcard-main {
    display: flex;
    flex-direction: column;
    align-items: center;
}

/* ================================================
   Flashcard Container
   ================================================ */

.flashcard-container {
    width: 100%;
    max-width: 420px;
}

/* Progress Bar */
.flashcard-progress {
    padding: 0.5rem 1rem;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.progress-bar {
    flex: 1;
    height: 4px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 999px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--gradient-primary);
    border-radius: 999px;
    transition: width var(--transition);
}

.progress-text {
    display: flex;
    align-items: center;
    gap: 0.2rem;
    font-size: 0.8rem;
    white-space: nowrap;
}

.progress-current {
    font-family: 'Space Grotesk', sans-serif;
    font-weight: 700;
    font-size: 1rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.progress-separator {
    color: var(--text-muted);
}

.progress-total {
    font-weight: 600;
    color: var(--text-secondary);
}

.progress-label {
    color: var(--text-muted);
    margin-left: 0.15rem;
}

/* Flashcard Deck */
.flashcard-deck {
    margin-bottom: 0.75rem;
}

.flashcard-wrapper {
    perspective: 1000px;
}

.flashcard-wrapper.hidden {
    display: none;
}

.flashcard {
    width: 100%;
    height: 280px;
    cursor: pointer;
}

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
    transform-style: preserve-3d;
}

.flashcard-inner.flipped {
    transform: rotateY(180deg);
}

.flashcard-front,
.flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 1.25rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--glass-border);
    overflow: hidden;
}

.flashcard-front {
    background: linear-gradient(145deg, rgba(102, 126, 234, 0.2), rgba(118, 75, 162, 0.2));
}

.flashcard-back {
    transform: rotateY(180deg);
    background: linear-gradient(145deg, rgba(240, 147, 251, 0.2), rgba(245, 87, 108, 0.2));
}

/* Card Decoration */
.card-decoration {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    overflow: hidden;
}

.decoration-circle {
    position: absolute;
    border-radius: 50%;
    opacity: 0.1;
}

.decoration-circle:first-child {
    width: 200px;
    height: 200px;
    background: var(--gradient-primary);
    top: -100px;
    right: -50px;
}

.decoration-circle:last-child {
    width: 150px;
    height: 150px;
    background: var(--gradient-accent);
    bottom: -75px;
    left: -50px;
}

/* Card Content */
.card-badges {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    z-index: 1;
}

.card-content {
    text-align: center;
    z-index: 1;
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.card-label {
    display: block;
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

.word-english,
.word-french {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 1.75rem;
    font-weight: 700;
    text-align: center;
    line-height: 1.3;
}

.word-french {
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.word-plural {
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-align: center;
    margin-top: 0.5rem;
    padding: 0.25rem 0.75rem;
    background: var(--glass-bg);
    border-radius: var(--radius-sm);
    display: inline-block;
}

.plural-label {
    font-weight: 600;
    color: var(--text-muted);
}

/* Speak Button */
.btn-speak {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.5rem 1rem;
    margin-top: 0.75rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    color: var(--text-color);
    font-size: 0.8rem;
    cursor: pointer;
    transition: var(--transition);
    z-index: 1;
}

.btn-speak:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: rgba(255, 255, 255, 0.2);
    transform: scale(1.05);
}

.speak-icon {
    font-size: 1rem;
}

/* Flip Hint */
.flip-hint {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
    z-index: 1;
}

.hint-icon {
    animation: tap-hint 1.5s ease-in-out infinite;
}

@keyframes tap-hint {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.2); }
}

/* Difficulty specific card colors */
.flashcard.flashcard-beginner .flashcard-front {
    background: linear-gradient(145deg, rgba(16, 185, 129, 0.15), rgba(16, 185, 129, 0.05));
}

.flashcard.flashcard-intermediate .flashcard-front {
    background: linear-gradient(145deg, rgba(245, 158, 11, 0.15), rgba(245, 158, 11, 0.05));
}

.flashcard.flashcard-advanced .flashcard-front {
    background: linear-gradient(145deg, rgba(239, 68, 68, 0.15), rgba(239, 68, 68, 0.05));
}

/* ================================================
   Flashcard Navigation
   ================================================ */

.flashcard-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.btn-nav {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.625rem 1.25rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    color: var(--text-color);
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition);
}

.btn-nav:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.12);
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.btn-nav:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.nav-arrow {
    font-size: 1.25rem;
    transition: transform var(--transition);
}

.btn-prev:hover:not(:disabled) .nav-arrow {
    transform: translateX(-3px);
}

.btn-next:hover:not(:disabled) .nav-arrow {
    transform: translateX(3px);
}

.nav-dots {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transition: var(--transition);
}

.nav-dot.active {
    background: var(--gradient-primary);
    transform: scale(1.25);
}

.nav-dot-more {
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* ================================================
   Badges
   ================================================ */

.difficulty-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.375rem 0.875rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.02em;
}

.difficulty-beginner {
    background: var(--beginner-bg);
    color: var(--beginner-color);
}

.difficulty-intermediate {
    background: var(--intermediate-bg);
    color: var(--intermediate-color);
}

.difficulty-advanced {
    background: var(--advanced-bg);
    color: var(--advanced-color);
}

.category-tag {
    display: inline-block;
    padding: 0.375rem 0.875rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 500;
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-secondary);
}

/* ================================================
   Empty State
   ================================================ */

.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    max-width: 400px;
    margin: 0 auto;
}

.empty-icon {
    font-size: 4rem;
    margin-bottom: 1.5rem;
    opacity: 0.7;
}

.empty-state h2 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
}

.empty-state p {
    color: var(--text-muted);
    margin-bottom: 1.5rem;
}

/* ================================================
   Utility Classes
   ================================================ */

.hidden {
    display: none !important;
}

/* ================================================
   Responsive Design
   ================================================ */

@media (max-width: 900px) {
    .feature-main {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .feature-visual {
        order: -1;
    }

    .feature-info {
        align-items: center;
    }

    .feature-list {
        align-items: flex-start;
        text-align: left;
    }

    .difficulty-grid {
        grid-template-columns: 1fr;
        max-width: 400px;
    }

    .flashcard-layout {
        grid-template-columns: 180px 1fr;
        gap: 1rem;
    }

    .filters-sidebar {
        padding: 0.75rem;
    }

    .filter-chip {
        padding: 0.25rem 0.5rem;
        font-size: 0.65rem;
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }

    .hero-stats {
        gap: 1.5rem;
    }

    .stat-number {
        font-size: 2rem;
    }

    .navbar .container {
        flex-direction: row;
        gap: 1rem;
    }

    .flashcard-layout {
        grid-template-columns: 1fr;
        gap: 0.75rem;
    }

    .filters-sidebar {
        position: static;
        max-height: none;
        padding: 0.75rem;
    }

    .sidebar-header {
        display: none;
    }

    .filter-form {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 1rem;
    }

    .filter-section {
        flex: 1;
        min-width: 140px;
    }

    .flashcard {
        height: 260px;
    }

    .word-english,
    .word-french {
        font-size: 1.5rem;
    }

    .categories-grid {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 2rem 0;
    }

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

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-stats {
        flex-direction: column;
        gap: 1rem;
    }

    .stat-divider {
        width: 40px;
        height: 1px;
    }

    .card-preview {
        width: 220px;
        height: 140px;
    }

    .preview-word,
    .preview-translation {
        font-size: 1.25rem;
    }

    .flashcard {
        height: 240px;
    }

    .word-english,
    .word-french {
        font-size: 1.35rem;
    }

    .flashcard-nav {
        gap: 0.5rem;
    }

    .btn-nav {
        padding: 0.5rem 0.875rem;
    }

    .nav-text {
        display: none;
    }

    .nav-dots {
        display: none;
    }

    .page-header {
        margin-bottom: 0.75rem;
    }

    .filters {
        padding: 0.625rem 1rem;
        margin-bottom: 0.75rem;
    }
}

/* ================================================
   Animations for Page Load
   ================================================ */

@keyframes slide-up {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.categories-section,
.difficulty-section,
.features-showcase {
    animation: slide-up 0.6s ease-out backwards;
}

.features-showcase {
    animation-delay: 0.2s;
}

.categories-section {
    animation-delay: 0.3s;
}

.difficulty-section {
    animation-delay: 0.4s;
}