* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: "Microsoft Yahei", sans-serif;
    color: #222;
    background-color: #ffffff;
    line-height: 1.7;
}
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}
nav {
    background: #f4f5f7;
    padding: 1rem 0;
    margin-bottom: 3rem;
}
nav .container a {
    margin-right: 24px;
    text-decoration: none;
    color: #2563eb;
    font-size:18px;
}
nav .container a:hover {
    text-decoration: underline;
}
h1 {
    font-size: 32px;
    margin-bottom:16px;
}
h2 {
    font-size:24px;
    margin:28px 0 12px;
}
p {
    margin-bottom:16px;
    font-size:17px;
}
ul {
    padding-left: 24px;
    margin-bottom:20px;
}
.card {
    border: 1px solid #e5e7eb;
    border-radius:8px;
    padding:20px;
    margin:16px 0;
}
footer {
    margin-top: 6rem;
    padding:2rem 0;
    border-top:1px solid #eee;
    color:#666;
    font-size:14px;
}
pre {
    background: #f4f5f7;
    padding:16px;
    border-radius:6px;
    overflow-x:auto;
    margin:16px 0;
}