/* 全局优雅书卷风格 */
:root {
    --paper-bg: #fdfaf5;
    --sidebar-bg: #f4eee0;
    --ink-black: #1a1a1a;
    --accent-red: #8b0000;
    --border-color: #d4c4ad;
    --text-main: #2c1e11;
}

body {
    margin: 0; padding: 0; height: 100vh;
    font-family: 'Noto Serif SC', serif;
    background-color: var(--paper-bg);
    color: var(--text-main);
    display: flex;
}

/* --- 左侧导航 --- */
nav {
    width: 280px; height: 100vh;
    background: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex; flex-direction: column;
    flex-shrink: 0; transition: transform 0.3s ease;
}

.nav-header { padding: 40px 20px; text-align: center; border-bottom: 1px solid rgba(0,0,0,0.05); }
.nav-header h1 { font-size: 1.5rem; letter-spacing: 4px; color: var(--accent-red); margin: 0; }

#chapter-links {
    flex: 1; overflow-y: auto; padding: 10px 0;
    scrollbar-width: thin;
}

#chapter-links a {
    display: block; padding: 12px 25px; color: var(--text-main);
    text-decoration: none; border-bottom: 1px solid rgba(0,0,0,0.03);
    transition: 0.2s; font-size: 0.95rem;
}

#chapter-links a:hover { background: #fff; padding-left: 35px; color: var(--accent-red); }
#chapter-links a.active { background: #fff; color: var(--accent-red); font-weight: bold; border-right: 4px solid var(--accent-red); }

/* 版权区域：移动端自动隐藏 */
.nav-footer {
    padding: 20px; border-top: 1px solid var(--border-color);
    font-size: 0.75rem; color: #8c7e6d; background: var(--sidebar-bg);
}

/* --- 右侧主内容 --- */
main { flex: 1; overflow-y: auto; scroll-behavior: smooth; }
.content-wrapper { max-width: 800px; margin: 0 auto; padding: 60px 40px; }

.original-box {
    font-size: 1.5rem; line-height: 2.2; padding: 40px;
    background: #fff; border: 1px solid var(--border-color);
    margin: 30px 0; box-shadow: 0 4px 12px rgba(0,0,0,0.02);
}

.commentary-text { font-size: 1.15rem; line-height: 2; text-align: justify; margin-bottom: 60px; }

/* 底部引用区域分割线 */
.references {
    margin-top: 100px; padding-top: 30px;
    border-top: 2px solid var(--accent-red); /* 实线分割 */
    font-size: 0.9rem; color: #666; opacity: 0.8;
}

/* --- 移动端响应式 --- */
@media (max-width: 768px) {
    body { flex-direction: column; }
    nav { width: 100%; height: auto; border-right: none; }
    .nav-footer { display: none; } /* 隐藏版权信息 */
    .nav-header { padding: 20px; }
    #chapter-links { display: flex; overflow-x: auto; white-space: nowrap; height: 50px; }
    #chapter-links a { border-bottom: none; border-right: 1px solid rgba(0,0,0,0.05); }
    .content-wrapper { padding: 30px 20px; }
    .original-box { padding: 20px; font-size: 1.2rem; }
}