:root {
    --primary-color: #4a90e2;
    --secondary-color: #7b68ee;
    --success-color: #4caf50;
    --warning-color: #ff9800;
    --danger-color: #f44336;
    --bg-color: #f5f7fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-light: #666666;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans CJK JP', 'Hiragino Sans', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    flex: 1;
}

header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 2rem 0;
    text-align: center;
    box-shadow: var(--shadow);
    position: relative;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

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

.language-selector {
    position: absolute;
    top: 1rem;
    right: 1rem;
}

.language-selector select {
    padding: 0.5rem 1rem;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 25px;
    background: rgba(255, 255, 255, 0.1);
    color: white;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.language-selector select:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.5);
}

.language-selector select option {
    background: var(--primary-color);
    color: white;
}

main {
    padding: 2rem 0;
}

.camera-section {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 2rem;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
    text-align: center;
}

#inputVideo, #outputCanvas {
    max-width: 100%;
    width: 640px;
    height: 480px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    background: #000;
}

#inputVideo {
    display: none;
}

.camera-controls {
    margin-top: 1.5rem;
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.camera-controls button {
    padding: 0.75rem 2rem;
    border: none;
    border-radius: 25px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    color: white;
}

#startBtn {
    background: var(--success-color);
}

#startBtn:hover:not(:disabled) {
    background: #45a049;
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

#stopBtn {
    background: var(--danger-color);
}

#stopBtn:hover:not(:disabled) {
    background: #e53935;
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

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

.learning-section {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.learning-section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
}

.lesson-card {
    background: linear-gradient(135deg, #f5f7fa 0%, #e9ecef 100%);
    border-radius: 15px;
    padding: 2rem;
    margin-bottom: 2rem;
}

.lesson-card h3 {
    color: var(--text-color);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.lesson-display {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: center;
}

.target-sign {
    text-align: center;
}

.target-sign span {
    font-size: 5rem;
    display: block;
    margin-bottom: 1rem;
}

.target-sign p {
    color: var(--text-light);
    font-size: 1.1rem;
}

.feedback-area {
    text-align: center;
}

.feedback {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    min-height: 2rem;
    color: var(--text-light);
}

.feedback.excellent {
    color: var(--success-color);
}

.feedback.good {
    color: var(--warning-color);
}

.accuracy-meter {
    width: 100%;
    height: 30px;
    background: var(--border-color);
    border-radius: 15px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.accuracy-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--danger-color), var(--warning-color), var(--success-color));
    width: 0%;
    transition: width 0.3s ease;
}

#accuracyText {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--primary-color);
}

.lesson-selector {
    margin-top: 2rem;
}

.lesson-selector h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

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

.lesson-btn {
    background: white;
    border: 2px solid var(--border-color);
    border-radius: 15px;
    padding: 1.5rem 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.lesson-btn:hover {
    border-color: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

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

.lesson-icon {
    font-size: 2rem;
}

.progress-section {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 2px solid var(--border-color);
}

.progress-section h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

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

.stat-card {
    background: linear-gradient(135deg, #f5f7fa 0%, #e9ecef 100%);
    padding: 1.5rem;
    border-radius: 15px;
    text-align: center;
}

.stat-label {
    display: block;
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.stat-value {
    display: block;
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary-color);
}

footer {
    background: var(--text-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: auto;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }
    
    .language-selector {
        position: static;
        margin-top: 1rem;
    }
    
    #inputVideo, #outputCanvas {
        width: 100%;
        height: auto;
        max-height: 400px;
    }
    
    .lesson-display {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .camera-controls {
        flex-direction: column;
    }
    
    .camera-controls button {
        width: 100%;
    }
}

/* アニメーション */
@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
    100% {
        transform: scale(1);
    }
}

.lesson-btn.active .lesson-icon {
    animation: pulse 2s infinite;
}

/* ダークモード対応（システム設定に従う） */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #1a1a1a;
        --card-bg: #2a2a2a;
        --text-color: #ffffff;
        --text-light: #cccccc;
        --border-color: #444444;
    }
    
    .lesson-card {
        background: linear-gradient(135deg, #2a2a2a 0%, #333333 100%);
    }
    
    .stat-card {
        background: linear-gradient(135deg, #2a2a2a 0%, #333333 100%);
    }
    
    .lesson-btn {
        background: var(--card-bg);
    }
    
    .lesson-btn.active {
        background: var(--primary-color);
    }
}