手机pc 居中

index.css

* {
    box-sizing: border-box;
}

html {
    padding: 0;
}

body {
    max-width: 700px;
    margin: 0 auto !important;
}

@media screen and  (min-width: 700px) {
    body {
        width: 700px; /*这是重点，pc居中*/
    }
}