:root {
    --primary-color: #00bcd4;
    --secondary-color: #0097a7;
    --accent-color: #ff6b6b;
    --background-color: #f5f5f5;
    --text-color: #333;
    --card-bg: #ffffff;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --border-radius: 12px;
}

* {
    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(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 40px;
    padding: 20px 0;
}

h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.subtitle {
    font-size: 1.2rem;
    color: #666;
}

.timer-section {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 40px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
    text-align: center;
}

.timer-display {
    margin-bottom: 30px;
}

.time {
    font-size: 4rem;
    font-weight: 700;
    color: var(--primary-color);
    font-variant-numeric: tabular-nums;
}

.temperature {
    margin-top: 10px;
    font-size: 1.1rem;
    color: #666;
}

.temp-value {
    color: var(--secondary-color);
    font-weight: 600;
}

.controls {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 100px;
}

.btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

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

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

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

.btn-tertiary {
    background: #e0e0e0;
    color: var(--text-color);
}

.stats-section {
    margin-bottom: 30px;
}

h2 {
    font-size: 1.8rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
}

.stat-card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform 0.3s ease;
}

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

.stat-label {
    font-size: 0.9rem;
    color: #666;
    margin-bottom: 5px;
}

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

.motivation-section {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 30px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

.motivation-text {
    font-size: 1.2rem;
    font-style: italic;
    color: #555;
    text-align: center;
}

.achievements-section {
    margin-bottom: 30px;
}

.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 20px;
}

.achievement {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: all 0.3s ease;
    position: relative;
}

.achievement:hover {
    transform: scale(1.05);
}

.achievement.locked {
    opacity: 0.5;
    filter: grayscale(1);
}

.achievement-icon {
    font-size: 3rem;
    margin-bottom: 10px;
}

.achievement-name {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-color);
}

.achievement-desc {
    font-size: 0.8rem;
    color: #666;
    margin-top: 5px;
}

footer {
    text-align: center;
    padding: 20px 0;
    margin-top: 40px;
}

.language-selector select {
    padding: 8px 16px;
    border: 1px solid #ddd;
    border-radius: 6px;
    background: white;
    font-size: 1rem;
    cursor: pointer;
}

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

.timer-display.active .time {
    animation: pulse 2s infinite;
}

/* レスポンシブ対応 */
@media (max-width: 600px) {
    h1 {
        font-size: 2rem;
    }
    
    .time {
        font-size: 3rem;
    }
    
    .timer-section {
        padding: 30px 20px;
    }
    
    .controls {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 200px;
    }
}

/* ダークモード対応 */
@media (prefers-color-scheme: dark) {
    :root {
        --background-color: #121212;
        --text-color: #e0e0e0;
        --card-bg: #1e1e1e;
        --shadow: 0 2px 10px rgba(0, 0, 0, 0.5);
    }
    
    .btn-tertiary {
        background: #333;
        color: #e0e0e0;
    }
    
    .language-selector select {
        background: #1e1e1e;
        color: #e0e0e0;
        border-color: #333;
    }
}