:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --text-color: #1f2937;
    --bg-color: #ffffff;
    --bg-secondary: #f3f4f6;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 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);
}

body.dark-theme {
    --text-color: #f3f4f6;
    --bg-color: #111827;
    --bg-secondary: #1f2937;
    --border-color: #374151;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.3), 0 1px 2px 0 rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
}

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

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

/* ヘッダー */
header {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav h1 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: 1rem;
}

.lang-switch, .theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-color);
    transition: all 0.3s;
}

.lang-switch:hover, .theme-toggle:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* メインコンテンツ */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* ヒーローセクション */
.hero {
    text-align: center;
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, #8b5cf6 100%);
    color: white;
    border-radius: 1rem;
    margin-bottom: 3rem;
}

.hero h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.hero p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.cta-button {
    background-color: white;
    color: var(--primary-color);
    border: none;
    padding: 1rem 2rem;
    font-size: 1.125rem;
    font-weight: 600;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: transform 0.3s, box-shadow 0.3s;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* 統計セクション */
.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-card {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    text-align: center;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-icon {
    font-size: 2.5rem;
    display: block;
    margin-bottom: 0.5rem;
}

.stat-card h3 {
    font-size: 0.875rem;
    color: var(--text-color);
    opacity: 0.7;
    margin-bottom: 0.5rem;
}

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

/* ゲームメニュー */
.game-menu h2 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 2rem;
}

.game-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.game-card {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow);
    transition: all 0.3s;
    text-align: center;
}

.game-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

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

.game-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.game-card p {
    font-size: 0.875rem;
    color: var(--text-color);
    opacity: 0.8;
    margin-bottom: 1.5rem;
}

.play-button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s;
}

.play-button:hover {
    background-color: var(--primary-hover);
}

/* ゲームエリア */
.game-area {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    min-height: 500px;
}

.game-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.back-button {
    background: none;
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    cursor: pointer;
    color: var(--text-color);
    transition: all 0.3s;
}

.back-button:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.game-info {
    display: flex;
    gap: 2rem;
    font-size: 1.125rem;
    font-weight: 600;
}

/* 記憶力ゲーム */
.memory-game {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    max-width: 400px;
    margin: 0 auto;
}

.memory-card {
    aspect-ratio: 1;
    position: relative;
    cursor: pointer;
    transform-style: preserve-3d;
    transition: transform 0.6s;
}

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

.card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    border-radius: 0.5rem;
    backface-visibility: hidden;
}

.card-front {
    background-color: var(--primary-color);
    color: white;
}

.card-back {
    background-color: var(--secondary-color);
    color: white;
    transform: rotateY(180deg);
}

/* 計算ゲーム */
.calc-game {
    max-width: 400px;
    margin: 0 auto;
    text-align: center;
}

.problem {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

.calc-input {
    width: 100%;
    padding: 1rem;
    font-size: 1.5rem;
    text-align: center;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    margin-bottom: 1rem;
    background-color: var(--bg-color);
    color: var(--text-color);
}

.submit-button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1.125rem;
    font-weight: 600;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background-color 0.3s;
}

.submit-button:hover {
    background-color: var(--primary-hover);
}

.feedback {
    margin-top: 1rem;
    font-size: 1.25rem;
    font-weight: 600;
    min-height: 2rem;
}

/* 反射神経ゲーム */
.reaction-game-container {
    min-height: 400px;
}

.reaction-game {
    position: relative;
    height: 400px;
    background-color: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    overflow: hidden;
}

.instruction {
    text-align: center;
    padding: 1rem;
    color: var(--text-color);
    opacity: 0.7;
}

.reaction-target {
    position: absolute;
    width: 50px;
    height: 50px;
    background-color: var(--danger-color);
    border-radius: 50%;
    cursor: pointer;
    animation: pulse 1s ease-in-out infinite;
}

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

/* パターン認識ゲーム */
.pattern-game-container {
    max-width: 400px;
    margin: 0 auto;
}

.pattern-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.5rem;
    margin-bottom: 2rem;
}

.pattern-cell {
    aspect-ratio: 1;
    background-color: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s;
}

.pattern-cell.active {
    background-color: var(--primary-color);
    transform: scale(0.95);
}

.pattern-cell.clicked {
    background-color: var(--secondary-color);
}

.start-pattern-button {
    width: 100%;
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem;
    font-size: 1.125rem;
    font-weight: 600;
    border-radius: 0.5rem;
    cursor: pointer;
    margin-bottom: 1rem;
    transition: background-color 0.3s;
}

.start-pattern-button:hover:not(:disabled) {
    background-color: var(--primary-hover);
}

.start-pattern-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.pattern-info {
    text-align: center;
    font-weight: 600;
    color: var(--primary-color);
}

/* 結果画面 */
.results {
    background-color: var(--bg-secondary);
    padding: 3rem;
    border-radius: 1rem;
    text-align: center;
    max-width: 500px;
    margin: 0 auto;
}

.results h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

.results-content {
    margin-bottom: 2rem;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    font-size: 1.125rem;
}

.result-item:last-child {
    border-bottom: none;
}

.result-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.retry-button, .menu-button {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.retry-button {
    background-color: var(--secondary-color);
    color: white;
}

.retry-button:hover {
    background-color: #059669;
}

.menu-button {
    background-color: var(--bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.menu-button:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* フッター */
footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-color);
    opacity: 0.7;
    border-top: 1px solid var(--border-color);
}

/* レスポンシブ */
@media (max-width: 768px) {
    nav {
        padding: 1rem;
    }
    
    .hero h2 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .game-grid {
        grid-template-columns: 1fr;
    }
    
    .memory-game {
        grid-template-columns: repeat(4, 1fr);
        max-width: 300px;
    }
    
    .memory-card {
        font-size: 1.5rem;
    }
}