body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
    background: #f5f5f5;
    color: #222;
}

a {
    color: inherit;
    text-decoration: none;
}

img {
    max-width: 100%;
    display: block;
}

header,
footer,
section,
div {
    box-sizing: border-box;
}