body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 20px;
    background: #f0f2f5;
    padding-bottom: 180px;
}
pre {
  line-height: 1.2;   
  font-weight: bold;    /* 粗体 */
  font-size: 30px; 
  white-space: pre-wrap;
  overflow-wrap: break-word;
  max-width: 100%;  /* 适配移动端 */
}
h1 {
    color: #2c3e50;
    text-align: center;
    margin-bottom: 30px;
    font-size: 2.2em;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
}

.chapters {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

.chapters h2 {
    grid-column: 1 / -1;
    margin-bottom: 15px;
}

.card {
    background: white;
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.2);
}

.zhangjie {
    display: block;
    text-align: center;
    padding: 15px;
    background: #3498db;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 500;
    transition: background 0.3s ease;
}

.zhangjie:hover {
    background: #2980b9;
}

footer {
    position: fixed;
    height:80px;
    margin-top: 40px;
    padding: 20px;
    background: #2c3e50;
    color: white;
    text-align: center;
    border-radius: 8px;
    bottom: 0;
    left: 0;
    width: 100%;
}

footer a {
    color: #3498db;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

mark {
    background: rgba(255,235,59,0.3);
    padding: 2px 5px;
    border-radius: 4px;
}