/* 移动端适配 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    max-width: 750px;
    margin: 0 auto;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* 底部导航栏 */
footer {
    position: fixed;
    bottom: 0;
    width: 100%;
    max-width: 750px;
    display: flex;
    justify-content: space-around;
    padding: 10px 0;
    background: #fff;
    box-shadow: 0 -2px 5px rgba(0,0,0,0.1);
}