/* --- 基础设置 (全局升级) --- */
:root {
    --primary-color: #2c3e50; /* 主色调 */
    --accent-color: #3498db;  /* 强调色 */
    --bg-color: #f7f9fc;      /* 升级：更干净的淡蓝灰背景 */
    --card-bg: #ffffff;
    --text-main: #2c3e50;
    --text-light: #7f8c8d;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.7; /* 增加行高，阅读更舒适 */
    margin: 0;
    padding: 30px 20px;
}

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

/* --- 链接与按钮 --- */
a { text-decoration: none; color: inherit; }

.back-link {
    display: inline-block;
    margin-bottom: 30px;
    color: var(--text-light);
    font-size: 0.95rem;
    transition: color 0.2s;
}
.back-link:hover { color: var(--accent-color); }

/* --- 头部样式 --- */
header {
    margin-bottom: 40px;
}

header h1 {
    font-size: 2rem;
    margin-bottom: 10px;
    background: linear-gradient(120deg, #2c3e50, #3498db);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
}

.series-tag {
    background-color: var(--accent-color);
    color: white;
    padding: 4px 10px;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: bold;
    text-transform: uppercase;
    letter-spacing: 1px;
    vertical-align: middle;
    margin-right: 10px;
}

.meta-info {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-top: 5px;
}

/* --- 卡片通用样式 (Article & Content) --- */
.content-card, .article-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 30px; /* 增加内边距 */
    margin-bottom: 30px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.03);
    border-top: 4px solid var(--accent-color); /* 顶部亮条 */
}

/* --- 语料文本区 --- */
.source-text {
    font-family: Georgia, "Times New Roman", serif;
    font-size: 1.15rem; /* 字号加大 */
    color: #2c3e50;
    line-height: 1.8;
    background-color: #fafafa;
    padding: 25px;
    border-left: 4px solid #dfe6e9; /* 左侧淡灰条 */
    border-radius: 4px;
    margin-bottom: 20px;
}

.img-fluid {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    display: block;
    margin: 20px auto;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

/* --- 问答交互区 --- */
.quiz-section h3 {
    border-bottom: 1px solid #eee;
    padding-bottom: 15px;
    margin-bottom: 25px;
    color: var(--primary-color);
}

.question-block {
    margin-bottom: 25px;
    padding-bottom: 25px;
    border-bottom: 1px dashed #eee;
}

.question-text {
    font-weight: 600;
    display: block;
    margin-bottom: 12px;
    color: #34495e;
}

.toggle-btn {
    background: white;
    border: 1px solid #bdc3c7;
    color: #7f8c8d;
    padding: 6px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s;
    outline: none;
}

.toggle-btn:hover {
    border-color: var(--accent-color);
    color: var(--accent-color);
    background-color: #f0f8ff;
}

.answer-box {
    display: none; /* 默认隐藏 */
    background-color: #f1f9fe; /* 极淡的蓝色背景 */
    padding: 20px;
    margin-top: 15px;
    border-radius: 8px;
    font-size: 0.95rem;
    color: #444;
    line-height: 1.6;
    border-left: 3px solid var(--accent-color);
}

.highlight {
    color: #e74c3c;
    font-weight: bold;
    background-color: rgba(231, 76, 60, 0.1);
    padding: 0 4px;
    border-radius: 3px;
}

/* --- 首页特定样式保留 --- */
.filter-container { /* ...你首页的筛选器样式... */ }
.article-grid { /* ...你首页的网格样式... */ }
/* (这些在首页index.html里已经写了inline样式，这里作为保底) */