/* Metro Master - Multi-City Metro Navigation Game */
:root {
    --primary: #003688;
    --primary-light: #0055cc;
    --secondary: #E32017;
    --background: #f5f5f5;
    --surface: #ffffff;
    --text: #1a1a1a;
    --text-secondary: #666666;
    --border: #e0e0e0;
    --success: #00782A;
    --warning: #FFD300;
    --error: #E32017;
    --shadow: 0 2px 8px rgba(0,0,0,0.1);
    --shadow-lg: 0 4px 20px rgba(0,0,0,0.15);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: all 0.3s ease;
}

/* ============================================
   CITY SELECTOR MODAL
   ============================================ */
.city-modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.city-modal.show {
    display: flex;
}

.city-modal-content {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    max-width: 800px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    text-align: center;
    animation: modalSlideIn 0.3s ease;
}

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

.city-modal-content h2 {
    font-size: 1.75rem;
    margin-bottom: 0.5rem;
    color: var(--text);
}

.city-modal-content > p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.city-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}

.city-card {
    background: var(--background);
    border-radius: var(--radius);
    padding: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    border: 3px solid transparent;
    text-align: left;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

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

.city-card.selected {
    border-color: var(--city-color, var(--primary));
    background: white;
}

.city-card-flag {
    font-size: 3rem;
    line-height: 1;
}

.city-card-info h3 {
    font-size: 1.25rem;
    margin-bottom: 0.25rem;
}

.city-card-info .city-system {
    font-weight: 600;
    color: var(--city-color, var(--primary));
    margin-bottom: 0.25rem;
}

.city-card-info .city-country {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.city-card-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.city-card-stats span {
    background: var(--surface);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* City Switcher Button */
.city-switcher {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    border-radius: 4px;
    color: white;
    padding: 0.25rem 0.5rem;
    cursor: pointer;
    margin-left: 0.5rem;
    font-size: 0.7rem;
    transition: var(--transition);
}

.city-switcher:hover {
    background: rgba(255, 255, 255, 0.3);
}

.city-flag {
    font-size: 1.5rem;
    margin-right: 0.25rem;
}

.city-switch-mobile {
    background: rgba(255, 255, 255, 0.1);
    margin-top: 0.5rem;
}

/* City Info Bar */
.city-info-bar {
    display: flex;
    justify-content: center;
    gap: 2rem;
    padding: 1rem;
    background: var(--surface);
    border-radius: var(--radius);
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

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

.city-stat-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.city-stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Fun Fact */
.fun-fact {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    padding: 1rem 1.5rem;
    border-radius: var(--radius);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: flex-start;
    gap: 1rem;
}

.fact-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.fun-fact p {
    font-size: 0.95rem;
    line-height: 1.5;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

/* Navbar */
.navbar {
    background: var(--primary);
    color: white;
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
}

.tube-icon {
    font-size: 1.5rem;
}

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

.nav-link {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
    background: rgba(255,255,255,0.15);
    color: white;
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: white;
    border-radius: 2px;
}

.mobile-menu {
    display: none;
    position: fixed;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--primary);
    padding: 1rem;
    z-index: 99;
}

.mobile-menu.show {
    display: block;
}

.mobile-link {
    display: block;
    color: white;
    text-decoration: none;
    padding: 1rem;
    border-radius: var(--radius-sm);
    margin-bottom: 0.5rem;
}

.mobile-link:hover {
    background: rgba(255,255,255,0.1);
}

/* Main Content */
.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.page {
    display: none;
    animation: fadeIn 0.3s ease;
}

.page.active {
    display: block;
}

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

/* Hero Section */
.hero {
    text-align: center;
    padding: 3rem 1rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    border-radius: var(--radius);
    margin-bottom: 2rem;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.hero p {
    opacity: 0.9;
    font-size: 1.1rem;
}

/* Game Mode Cards */
.game-modes {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.mode-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
    border: 2px solid transparent;
}

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

.mode-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.mode-card h3 {
    margin-bottom: 0.5rem;
    color: var(--primary);
}

.mode-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.mode-difficulty {
    display: inline-block;
    background: var(--background);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Stats Preview */
.stats-preview {
    display: flex;
    justify-content: center;
    gap: 3rem;
    padding: 2rem;
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

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

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
}

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

/* Page Headers */
.page-header {
    text-align: center;
    margin-bottom: 2rem;
}

.page-header h2 {
    color: var(--primary);
    margin-bottom: 0.5rem;
}

.page-header p {
    color: var(--text-secondary);
}

/* Quiz Styles */
.quiz-setup {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    text-align: center;
    box-shadow: var(--shadow);
}

.quiz-setup h3 {
    margin-bottom: 1.5rem;
}

.difficulty-selector {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}

.diff-btn {
    padding: 1rem 1.5rem;
    border: 2px solid var(--border);
    background: var(--surface);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
}

.diff-btn:hover {
    border-color: var(--primary);
}

.diff-btn.active {
    border-color: var(--primary);
    background: var(--primary);
    color: white;
}

/* Buttons */
.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-secondary {
    background: var(--background);
    color: var(--text);
    border: 2px solid var(--border);
    padding: 1rem 2rem;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-large {
    padding: 1.25rem 3rem;
    font-size: 1.1rem;
}

/* Quiz Game */
.quiz-game {
    max-width: 600px;
    margin: 0 auto;
}

.quiz-progress {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: var(--border);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--primary);
    transition: width 0.3s ease;
}

.quiz-question-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    margin-bottom: 1rem;
}

.color-hint {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    margin: 0 auto 1rem;
    border: 3px solid var(--border);
}

.quiz-question-card h3 {
    text-align: center;
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
}

.quiz-options {
    display: grid;
    gap: 0.75rem;
}

.option-btn {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--border);
    background: var(--surface);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
    text-align: left;
}

.option-btn:hover {
    border-color: var(--primary);
    background: rgba(0, 54, 136, 0.05);
}

.option-btn.correct {
    border-color: var(--success);
    background: rgba(0, 120, 42, 0.1);
}

.option-btn.incorrect {
    border-color: var(--error);
    background: rgba(227, 32, 23, 0.1);
}

.quiz-score {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
}

/* Quiz Results */
.quiz-results {
    max-width: 500px;
    margin: 0 auto;
}

.results-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 3rem 2rem;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.results-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.results-score {
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

.big-score {
    font-size: 4rem;
    font-weight: 700;
    color: var(--primary);
}

.results-message {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.xp-earned {
    background: linear-gradient(135deg, var(--success) 0%, #00a854 100%);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 20px;
    display: inline-block;
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.results-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* Memory Game */
.memory-instructions {
    background: var(--background);
    padding: 1rem;
    border-radius: var(--radius-sm);
    margin-bottom: 1.5rem;
}

.memory-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
}

.memory-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

.memory-card {
    aspect-ratio: 1;
    perspective: 1000px;
    cursor: pointer;
}

.memory-card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.5s;
    transform-style: preserve-3d;
}

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

.memory-card-front,
.memory-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.9rem;
    text-align: center;
    padding: 0.5rem;
}

.memory-card-front {
    background: var(--primary);
    color: white;
    font-size: 2rem;
}

.memory-card-back {
    background: var(--surface);
    border: 2px solid var(--border);
    transform: rotateY(180deg);
}

.memory-card-back.color-card {
    border: none;
}

.memory-card.matched .memory-card-back {
    border-color: var(--success);
    box-shadow: 0 0 10px rgba(0, 120, 42, 0.3);
}

/* Route Challenge */
.route-challenge {
    max-width: 600px;
    margin: 0 auto;
}

.route-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.route-endpoints {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.endpoint {
    flex: 1;
    text-align: center;
}

.endpoint-label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.endpoint-station {
    display: block;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary);
}

.route-arrow {
    font-size: 1.5rem;
    color: var(--text-secondary);
}

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

.route-answer {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.route-answer h4 {
    margin-bottom: 1rem;
}

.line-selector {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.line-chip {
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
    color: white;
    font-weight: 500;
    font-size: 0.9rem;
}

.line-chip.selected {
    border-color: var(--text);
    transform: scale(1.05);
}

.suggested-route {
    margin: 1rem 0;
    padding: 1rem;
    background: var(--background);
    border-radius: var(--radius-sm);
}

/* Explore Page */
.explore-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    justify-content: center;
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    background: var(--surface);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
}

.tab-btn:hover {
    background: var(--border);
}

.tab-btn.active {
    background: var(--primary);
    color: white;
}

.search-box {
    margin-bottom: 1.5rem;
}

.search-box input {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    outline: none;
    transition: var(--transition);
}

.search-box input:focus {
    border-color: var(--primary);
}

.explore-content {
    animation: fadeIn 0.3s ease;
}

/* Lines Grid - Accordion Style */
.lines-grid {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.line-accordion {
    background: var(--surface);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.accordion-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.25rem;
    cursor: pointer;
    transition: var(--transition);
}

.accordion-header:hover {
    filter: brightness(0.95);
}

.accordion-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 600;
    font-size: 1.1rem;
}

.line-color-bar {
    width: 6px;
    height: 30px;
    border-radius: 3px;
}

.accordion-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.station-count {
    font-size: 0.9rem;
    opacity: 0.9;
}

.accordion-icon {
    font-size: 0.8rem;
    transition: transform 0.3s ease;
}

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
    background: var(--background);
}

.accordion-content.open {
    max-height: 600px;
    overflow-y: auto;
}

.stations-scroll {
    padding: 1rem;
}

.station-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 0;
    position: relative;
}

.station-marker {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    flex-shrink: 0;
    z-index: 1;
}

.station-connector {
    position: absolute;
    left: 5px;
    top: 0;
    bottom: 0;
    width: 2px;
}

.station-row:first-child .station-connector {
    top: 50%;
}

.station-row:last-child .station-connector {
    bottom: 50%;
}

.station-name-text {
    font-size: 0.95rem;
}

.interchange-indicator {
    color: var(--warning);
    font-size: 0.9rem;
    margin-left: auto;
}

/* Station & Interchange Accordions */
.station-accordion,
.interchange-accordion {
    background: var(--surface);
    border-radius: var(--radius-sm);
    margin-bottom: 0.5rem;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.station-accordion-header,
.interchange-accordion-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.25rem;
    cursor: pointer;
    transition: var(--transition);
}

.station-accordion-header:hover,
.interchange-accordion-header:hover {
    background: var(--background);
}

.accordion-icon-small {
    font-size: 0.7rem;
    margin-left: 0.5rem;
    color: var(--text-secondary);
}

.station-accordion-content,
.interchange-accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
    background: var(--background);
}

.station-accordion-content.open,
.interchange-accordion-content.open {
    max-height: 300px;
}

.station-detail-card {
    padding: 1rem 1.25rem;
}

.interchange-label {
    background: linear-gradient(135deg, var(--warning) 0%, #ffb347 100%);
    color: #333;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.85rem;
    display: inline-block;
    margin-bottom: 1rem;
}

.lines-served {
    font-size: 0.9rem;
}

.lines-served strong {
    display: block;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.line-detail-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border);
}

.line-detail-row:last-child {
    border-bottom: none;
}

.line-color-chip {
    width: 24px;
    height: 24px;
    border-radius: 4px;
}

.line-detail-name {
    font-weight: 500;
}

/* Legacy styles for backward compatibility */
.stations-list,
.interchanges-list {
    display: flex;
    flex-direction: column;
    gap: 0;
}

.station-item,
.interchange-item {
    background: var(--surface);
    border-radius: var(--radius-sm);
    padding: 1rem 1.5rem;
    box-shadow: var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.station-name {
    font-weight: 500;
}

.station-lines {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.line-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.interchange-badge {
    background: var(--warning);
    color: var(--text);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-right: 0.5rem;
}

/* Profile Page */
.profile-card {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.profile-avatar {
    width: 80px;
    height: 80px;
    background: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
}

.profile-info h3 {
    margin-bottom: 0.5rem;
}

.level-badge {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
}

.xp-progress {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.xp-bar {
    height: 12px;
    background: var(--border);
    border-radius: 6px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.xp-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 100%);
    transition: width 0.5s ease;
}

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

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    box-shadow: var(--shadow);
}

.stat-card .stat-icon {
    font-size: 1.5rem;
    display: block;
    margin-bottom: 0.5rem;
}

.stat-card .stat-value {
    display: block;
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 0.25rem;
}

.stat-card .stat-name {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.achievements-section h3 {
    margin-bottom: 1rem;
}

.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 1rem;
}

.achievement-card {
    background: var(--surface);
    border-radius: var(--radius-sm);
    padding: 1rem;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
    opacity: 0.5;
    filter: grayscale(1);
}

.achievement-card.unlocked {
    opacity: 1;
    filter: none;
    border: 2px solid var(--success);
}

.achievement-icon {
    font-size: 1.5rem;
}

.achievement-info h4 {
    font-size: 0.9rem;
    margin-bottom: 0.25rem;
}

.achievement-info p {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 1000;
}

.toast {
    background: var(--surface);
    padding: 1rem 1.5rem;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    margin-top: 0.5rem;
    animation: slideIn 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.toast.success {
    border-left: 4px solid var(--success);
}

.toast.error {
    border-left: 4px solid var(--error);
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .main-content {
        padding: 1rem;
    }
    
    .hero h1 {
        font-size: 1.75rem;
    }
    
    .game-modes {
        grid-template-columns: 1fr;
    }
    
    .stats-preview {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .difficulty-selector {
        flex-direction: column;
    }
    
    .diff-btn {
        width: 100%;
    }
    
    .results-actions {
        flex-direction: column;
    }
    
    .memory-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 0.5rem;
    }
    
    .route-endpoints {
        flex-direction: column;
    }
    
    .route-arrow {
        transform: rotate(90deg);
    }
    
    .profile-card {
        flex-direction: column;
        text-align: center;
    }
    
    .toast-container {
        left: 1rem;
        right: 1rem;
        bottom: 1rem;
    }
}

@media (max-width: 480px) {
    .navbar {
        padding: 1rem;
    }
    
    .memory-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .memory-card-back {
        font-size: 0.75rem;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}