* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Helvetica, "PingFang SC", "Microsoft Yahei", sans-serif;
}
article {
    margin: 30px auto;
    width: 640px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}
h1 {
    text-align: center;
}
p {
    line-height: 1.9;
    text-indent: 2em;
}