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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: #333;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    width: 90%;
    max-width: 600px;
    text-align: center;
}

h1 {
    color: #2c3e50;
    margin-bottom: 30px;
    font-size: 28px;
    font-weight: 700;
}

/* 谱号显示区域 */
.stave-container {
    background: #f8f9fa;
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 30px;
    border: 2px dashed #dee2e6;
    min-height: 120px;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* 选择题区域 */
.options-container {
    margin-bottom: 20px;
}

.question {
    font-size: 18px;
    font-weight: 600;
    color: #495057;
    margin-bottom: 15px;
}

.options {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
    gap: 12px;
}

.option-btn {
    flex: 1;
    min-width: 0;
}

.option-btn {
    background: #e9ecef;
    border: none;
    padding: 15px;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    color: #495057;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: left;
}

.option-btn:hover {
    background: #dee2e6;
    transform: translateY(-2px);
}

.option-btn:active {
    transform: translateY(0);
}

/* 错误反馈状态 */
.option-btn.error {
    background: #f8d7da !important;
    color: #721c24 !important;
    border-color: #f5c6cb !important;
}

.option-btn.disabled {
    background: #e9ecef !important;
    color: #6c757d !important;
    cursor: not-allowed !important;
    opacity: 0.6;
}

/* 反馈区域 */
.feedback {
    min-height: 40px;
    margin-bottom: 20px;
    font-size: 18px;
    font-weight: 700;
}

.feedback.correct {
    color: #28a745;
}

.feedback.wrong {
    color: #dc3545;
}

/* 控制按钮 */
.controls {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 20px;
}

.btn {
    background: #007bff;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s ease;
}

.btn:hover {
    background: #0056b3;
}

.btn.secondary {
    background: #6c757d;
}

.btn.secondary:hover {
    background: #545b62;
}

/* 进度条显示 */
.progress-container {
    margin-bottom: 20px;
}

/* 隐藏进度条 */
.progress-container.hidden {
    display: none;
}

.progress-text {
    font-size: 16px;
    color: #6c757d;
    font-weight: 600;
    margin-bottom: 8px;
    text-align: left;
}

.progress-bar-container {
    width: 100%;
    height: 20px;
    background: #e9ecef;
    border-radius: 10px;
    overflow: hidden;
    position: relative;
}

.progress-bar {
    height: 100%;
    width: 0%;
    border-radius: 10px;
    transition: all 0.3s ease;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.1);
}

/* 进度条颜色类 */
.progress-bar.red {
    background: linear-gradient(90deg, #dc3545, #c82333);
}

.progress-bar.orange {
    background: linear-gradient(90deg, #fd7e14, #e8590c);
}

.progress-bar.green {
    background: linear-gradient(90deg, #28a745, #20c997);
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

/* 响应式设计 */
@media (max-width: 480px) {
    .container {
        padding: 20px;
        width: 95%;
    }
    
    h1 {
        font-size: 24px;
    }
    
    .options {
        grid-template-columns: 1fr;
    }
    
    .controls {
        flex-direction: column;
    }
}