/**
 * 알파벳 단어 (Alphabet Word) - Main Stylesheet
 * Cosmic color scheme with Ridibooks-inspired design
 * Version: 1.0.0
 */

/* ============================================
   CSS CUSTOM PROPERTIES (VARIABLES)
   ============================================ */
:root {
    /* Primary Colors - Cosmic Theme */
    --primary: #667eea;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --secondary: #764ba2;
    --accent: #f093fb;
    --accent-alt: #f5576c;

    /* Cosmic Gradient */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-cosmic: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    --gradient-dark: linear-gradient(180deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
    --gradient-card: linear-gradient(145deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.05));

    /* Text Colors */
    --text-primary: #1f2937;
    --text-secondary: #4b5563;
    --text-muted: #9ca3af;
    --text-light: #f9fafb;
    --text-on-gradient: #ffffff;

    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f3f4f6;
    --bg-tertiary: #e5e7eb;
    --bg-dark: #111827;
    --bg-card: #ffffff;
    --bg-overlay: rgba(0, 0, 0, 0.5);

    /* Border Colors */
    --border-light: #e5e7eb;
    --border-medium: #d1d5db;
    --border-dark: #374151;

    /* Status Colors */
    --success: #10b981;
    --success-light: #d1fae5;
    --warning: #f59e0b;
    --warning-light: #fef3c7;
    --error: #ef4444;
    --error-light: #fee2e2;
    --info: #3b82f6;
    --info-light: #dbeafe;

    /* Game Colors */
    --game-easy: #22c55e;
    --game-medium: #f59e0b;
    --game-hard: #ef4444;
    --game-score: #8b5cf6;
    --game-timer: #06b6d4;
    --game-combo: #ec4899;

    /* Typography */
    --font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-family-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
    --font-family-display: 'Poppins', var(--font-family);

    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    --font-size-6xl: 3.75rem;

    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --font-weight-extrabold: 800;

    --line-height-tight: 1.25;
    --line-height-snug: 1.375;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.625;
    --line-height-loose: 2;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;

    /* Shadows */
    --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);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --shadow-cosmic: 0 10px 40px rgba(102, 126, 234, 0.3);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.5);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    --transition-bounce: 500ms cubic-bezier(0.68, -0.55, 0.265, 1.55);

    /* Z-index */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-fixed: 300;
    --z-modal-backdrop: 400;
    --z-modal: 500;
    --z-popover: 600;
    --z-tooltip: 700;
    --z-loading: 800;

    /* Container */
    --container-max: 1200px;
    --container-wide: 1400px;
    --container-narrow: 800px;

    /* Header */
    --header-height: 70px;
    --header-height-mobile: 60px;
}

/* Dark mode variables */
[data-theme="dark"] {
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-muted: #6b7280;
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-tertiary: #374151;
    --bg-card: #1f2937;
    --border-light: #374151;
    --border-medium: #4b5563;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-family-display);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--text-primary);
    margin-bottom: var(--space-md);
}

h1 {
    font-size: var(--font-size-4xl);
}

h2 {
    font-size: var(--font-size-3xl);
}

h3 {
    font-size: var(--font-size-2xl);
}

h4 {
    font-size: var(--font-size-xl);
}

h5 {
    font-size: var(--font-size-lg);
}

h6 {
    font-size: var(--font-size-base);
}

p {
    margin-bottom: var(--space-md);
    color: var(--text-secondary);
}

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

a:hover {
    color: var(--primary-dark);
}

strong, b {
    font-weight: var(--font-weight-semibold);
}

small {
    font-size: var(--font-size-sm);
}

/* ============================================
   LAYOUT
   ============================================ */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.container-wide {
    max-width: var(--container-wide);
}

.container-narrow {
    max-width: var(--container-narrow);
}

.section {
    padding: var(--space-4xl) 0;
}

.section-sm {
    padding: var(--space-2xl) 0;
}

.section-lg {
    padding: var(--space-4xl) 0;
}

/* ============================================
   HEADER
   ============================================ */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-light);
    z-index: var(--z-fixed);
    transition: all var(--transition-base);
}

.site-header.scrolled {
    box-shadow: var(--shadow-md);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: var(--container-wide);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

/* Logo */
.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    text-decoration: none;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--gradient-primary);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    color: white;
    font-weight: var(--font-weight-bold);
    box-shadow: var(--shadow-cosmic);
}

.logo-text {
    font-family: var(--font-family-display);
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Navigation */
.main-nav {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
}

.nav-item {
    position: relative;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-md);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover {
    color: var(--primary);
    background: rgba(102, 126, 234, 0.1);
}

.nav-link.active {
    color: var(--primary);
    background: rgba(102, 126, 234, 0.1);
}

.nav-link .icon {
    font-size: var(--font-size-xs);
    transition: transform var(--transition-fast);
}

.nav-item:hover .nav-link .icon {
    transform: rotate(180deg);
}

/* Dropdown Menu */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    min-width: 200px;
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--border-light);
    padding: var(--space-sm);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast);
    z-index: var(--z-dropdown);
}

.nav-item:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-md);
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.dropdown-item:hover {
    color: var(--primary);
    background: rgba(102, 126, 234, 0.1);
}

.dropdown-item .emoji {
    font-size: var(--font-size-lg);
}

/* Header Actions */
.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-sm);
}

.hamburger {
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    width: 24px;
    height: 20px;
}

.hamburger span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.mobile-menu-toggle.active .hamburger span:nth-child(1) {
    transform: translateY(9px) rotate(45deg);
}

.mobile-menu-toggle.active .hamburger span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active .hamburger span:nth-child(3) {
    transform: translateY(-9px) rotate(-45deg);
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-lg);
    font-family: var(--font-family);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    line-height: 1;
    text-decoration: none;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

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

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

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

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

.btn-secondary:hover {
    background: var(--bg-tertiary);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

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

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

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

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

.btn-danger:hover {
    background: #dc2626;
}

.btn-success {
    background: var(--success);
    color: white;
}

.btn-success:hover {
    background: #059669;
}

/* Button Sizes */
.btn-sm {
    padding: var(--space-xs) var(--space-md);
    font-size: var(--font-size-xs);
}

.btn-lg {
    padding: var(--space-md) var(--space-xl);
    font-size: var(--font-size-base);
    border-radius: var(--radius-xl);
}

.btn-xl {
    padding: var(--space-lg) var(--space-2xl);
    font-size: var(--font-size-lg);
    border-radius: var(--radius-2xl);
}

.btn-block {
    width: 100%;
}

/* Button with Icon */
.btn-icon {
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: var(--radius-full);
}

/* ============================================
   CARDS
   ============================================ */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: all var(--transition-base);
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.card-image {
    width: 100%;
    aspect-ratio: 16/9;
    object-fit: cover;
}

.card-body {
    padding: var(--space-lg);
}

.card-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-sm);
}

.card-text {
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
}

.card-footer {
    padding: var(--space-md) var(--space-lg);
    border-top: 1px solid var(--border-light);
    background: var(--bg-secondary);
}

/* Cosmic Card */
.card-cosmic {
    background: var(--gradient-card);
    border: 1px solid rgba(102, 126, 234, 0.2);
}

.card-cosmic:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-cosmic);
}

/* ============================================
   FORMS
   ============================================ */
.form-group {
    margin-bottom: var(--space-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--space-sm);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-primary);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--space-md);
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    color: var(--text-primary);
    background: var(--bg-primary);
    border: 2px solid var(--border-light);
    border-radius: var(--radius-lg);
    transition: all var(--transition-fast);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.2);
}

.form-input::placeholder,
.form-textarea::placeholder {
    color: var(--text-muted);
}

.form-textarea {
    min-height: 120px;
    resize: vertical;
}

.form-help {
    margin-top: var(--space-xs);
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.form-error {
    margin-top: var(--space-xs);
    font-size: var(--font-size-sm);
    color: var(--error);
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: calc(var(--header-height) + var(--space-2xl)) var(--space-lg) var(--space-2xl);
    background: var(--gradient-dark);
    overflow: hidden;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    max-width: 800px;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-xs) var(--space-md);
    background: rgba(102, 126, 234, 0.2);
    border: 1px solid rgba(102, 126, 234, 0.3);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    color: var(--primary-light);
    margin-bottom: var(--space-lg);
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: var(--font-weight-extrabold);
    color: white;
    margin-bottom: var(--space-lg);
    line-height: var(--line-height-tight);
}

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

.hero-description {
    font-size: var(--font-size-xl);
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: var(--space-2xl);
    line-height: var(--line-height-relaxed);
}

.hero-buttons {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-md);
    flex-wrap: wrap;
}

/* ============================================
   SLIDER
   ============================================ */
.slider-section {
    padding: var(--space-3xl) 0;
    background: var(--bg-secondary);
}

.slider-container {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-2xl);
}

.slider-track {
    display: flex;
    transition: transform 500ms ease;
}

.slide {
    flex: 0 0 100%;
    min-width: 100%;
}

.slide-content {
    position: relative;
    padding: var(--space-3xl);
    background: var(--gradient-primary);
    border-radius: var(--radius-2xl);
    color: white;
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-2xl);
    overflow: hidden;
}

.slide-text {
    flex: 1;
    max-width: 500px;
}

.slide-title {
    font-size: var(--font-size-3xl);
    color: white;
    margin-bottom: var(--space-md);
}

.slide-description {
    font-size: var(--font-size-lg);
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--space-xl);
}

.slide-image {
    flex: 1;
    max-width: 400px;
}

.slide-image img {
    width: 100%;
    height: auto;
    filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.3));
}

/* Slider Controls */
.slider-controls {
    position: absolute;
    bottom: var(--space-lg);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.slider-dot {
    width: 10px;
    height: 10px;
    background: rgba(255, 255, 255, 0.4);
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.slider-dot.active {
    width: 30px;
    background: white;
}

.slider-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.2);
    border: none;
    border-radius: var(--radius-full);
    color: white;
    font-size: var(--font-size-xl);
    cursor: pointer;
    transition: all var(--transition-fast);
    backdrop-filter: blur(5px);
}

.slider-arrow:hover {
    background: rgba(255, 255, 255, 0.3);
}

.slider-arrow.prev {
    left: var(--space-lg);
}

.slider-arrow.next {
    right: var(--space-lg);
}

/* ============================================
   GAME SECTION
   ============================================ */
.game-section {
    padding: var(--space-4xl) 0;
}

.game-header {
    text-align: center;
    margin-bottom: var(--space-2xl);
}

.game-container {
    max-width: 800px;
    margin: 0 auto;
}

.game-board {
    background: var(--gradient-card);
    border: 1px solid rgba(102, 126, 234, 0.2);
    border-radius: var(--radius-2xl);
    padding: var(--space-2xl);
    margin-bottom: var(--space-xl);
}

.game-stats {
    display: flex;
    justify-content: space-around;
    margin-bottom: var(--space-xl);
}

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

.stat-value {
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

/* Letter Tiles */
.letter-tiles {
    display: flex;
    justify-content: center;
    gap: var(--space-sm);
    margin: var(--space-xl) 0;
    flex-wrap: wrap;
}

.letter-tile {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    font-family: var(--font-family-mono);
    text-transform: uppercase;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-md);
}

.letter-tile:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-cosmic);
}

.letter-tile.selected {
    background: var(--gradient-secondary);
    transform: scale(0.95);
}

.letter-tile.disabled {
    opacity: 0.3;
    cursor: not-allowed;
    transform: none;
}

/* Answer Display */
.answer-display {
    min-height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xs);
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--space-md);
    margin-bottom: var(--space-xl);
}

.answer-letter {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    font-family: var(--font-family-mono);
    text-transform: uppercase;
    background: white;
    color: var(--text-primary);
    border: 2px solid var(--border-light);
    border-radius: var(--radius-md);
}

.answer-letter.correct {
    background: var(--success-light);
    border-color: var(--success);
    color: var(--success);
}

.answer-letter.wrong {
    background: var(--error-light);
    border-color: var(--error);
    color: var(--error);
}

/* Game Controls */
.game-controls {
    display: flex;
    justify-content: center;
    gap: var(--space-md);
}

/* Difficulty Badge */
.difficulty-badge {
    display: inline-flex;
    align-items: center;
    padding: var(--space-xs) var(--space-md);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    border-radius: var(--radius-full);
}

.difficulty-badge.easy {
    background: var(--success-light);
    color: var(--game-easy);
}

.difficulty-badge.medium {
    background: var(--warning-light);
    color: var(--game-medium);
}

.difficulty-badge.hard {
    background: var(--error-light);
    color: var(--game-hard);
}

/* ============================================
   WORD CARDS (Ridibooks Style)
   ============================================ */
.word-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--space-lg);
}

.word-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: var(--space-lg);
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
    cursor: pointer;
}

.word-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.word-english {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    font-family: var(--font-family-mono);
    color: var(--primary);
    margin-bottom: var(--space-sm);
}

.word-korean {
    font-size: var(--font-size-base);
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
}

.word-meta {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
}

.word-category {
    padding: var(--space-xs) var(--space-sm);
    font-size: var(--font-size-xs);
    background: var(--bg-secondary);
    border-radius: var(--radius-full);
    color: var(--text-muted);
}

/* Speaker Button */
.btn-speak {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-speak:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-cosmic);
}

/* ============================================
   BLOG / ARTICLES
   ============================================ */
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--space-xl);
}

.blog-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
}

.blog-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
}

.blog-image {
    width: 100%;
    aspect-ratio: 16/9;
    object-fit: cover;
}

.blog-content {
    padding: var(--space-lg);
}

.blog-meta {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    margin-bottom: var(--space-sm);
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.blog-category {
    padding: var(--space-xs) var(--space-sm);
    background: rgba(102, 126, 234, 0.1);
    color: var(--primary);
    border-radius: var(--radius-full);
    font-weight: var(--font-weight-medium);
}

.blog-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
}

.blog-title a {
    color: inherit;
}

.blog-title a:hover {
    color: var(--primary);
}

.blog-excerpt {
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* ============================================
   FOOTER
   ============================================ */
.site-footer {
    background: var(--bg-dark);
    color: var(--text-light);
    padding: var(--space-4xl) 0 var(--space-xl);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: var(--space-2xl);
    margin-bottom: var(--space-3xl);
}

.footer-brand {
    max-width: 300px;
}

.footer-brand .logo {
    margin-bottom: var(--space-md);
}

.footer-brand p {
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: var(--space-lg);
}

.footer-title {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: white;
    margin-bottom: var(--space-lg);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--space-sm);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    font-size: var(--font-size-sm);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: var(--space-xl);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.copyright {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.5);
}

.social-links {
    display: flex;
    gap: var(--space-sm);
}

.social-link {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary);
    transform: translateY(-2px);
}

/* ============================================
   LOADING SCREEN
   ============================================ */
.loading-screen {
    position: fixed;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--gradient-dark);
    z-index: var(--z-loading);
    transition: opacity 0.5s ease, visibility 0.5s ease;
}

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

.loading-spinner {
    width: 60px;
    height: 60px;
    border: 3px solid rgba(255, 255, 255, 0.1);
    border-top-color: var(--primary);
    border-radius: var(--radius-full);
    animation: spin 1s linear infinite;
}

.loading-text {
    margin-top: var(--space-lg);
    color: white;
    font-size: var(--font-size-lg);
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* ============================================
   UTILITIES
   ============================================ */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--primary); }
.text-secondary { color: var(--text-secondary); }
.text-muted { color: var(--text-muted); }
.text-success { color: var(--success); }
.text-warning { color: var(--warning); }
.text-error { color: var(--error); }

.bg-primary { background-color: var(--bg-primary); }
.bg-secondary { background-color: var(--bg-secondary); }
.bg-dark { background-color: var(--bg-dark); }

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

.hidden { display: none !important; }
.invisible { visibility: hidden; }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }

.p-sm { padding: var(--space-sm); }
.p-md { padding: var(--space-md); }
.p-lg { padding: var(--space-lg); }
.p-xl { padding: var(--space-xl); }

.rounded { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-xl { border-radius: var(--radius-xl); }
.rounded-full { border-radius: var(--radius-full); }

.shadow { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }
.shadow-cosmic { box-shadow: var(--shadow-cosmic); }

/* Screen reader only */
.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;
}

/* Main content padding for fixed header */
main {
    padding-top: var(--header-height);
}