body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
        "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f5f5;
}

.container {
    /* width: 94%; */
    max-width: 1200px;
    margin: 0 auto;
}

header {
    background: linear-gradient(to right, #5f91ec, #5fb4ec);
    color: white;
    padding: 2rem 1rem;
    text-align: center;
    box-shadow: 0px 5px 5px rgba(0, 0, 0, 0.15);
    margin-bottom: 1rem;
}

header .description {
    text-align: center;
    font-style: italic;
    padding: 0 10rem;
}

header a,
header a:visited {
    color: #fff;
}

main {
    /* 让main元素占据所有剩余的垂直空间，从而将footer推到底部 */
    flex: 1;
}

h1 {
    text-align: center;
    font-size: 1.8rem;
}

h2 {
    font-size: 1.6rem;
}

a,
a:visited {
    text-decoration: none;
    color: blue;
}

footer {
    background-color: #5f91ec;
    color: #eee;
    padding: 3rem 1rem;
}

footer .name {
    font-size: 0.97rem;
    /* font-weight: bold; */
}

footer a,
footer a:visited {
    color: #fff;
}

footer .columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

footer .column {
    margin: 0.6rem 0;
}

footer .end {
    text-align: right;
}

/* 针对小屏幕设备添加媒体查询 */
@media (max-width: 768px) {
    header .description {
        padding: 0.5rem;
    }

    footer {
        padding: 1.5rem;
    }
}