* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: #f5f5f5;
    color: #333;
    line-height: 1.6;
}
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; }