CSS0013： CSS 通用样式

1，

/* 通用样式 */

*,::after,::before {
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box
}

::-webkit-scrollbar {
    width: 0;
    height: 0;
    background-color: #f5f5f5
}

html {
    width: 100%;
    min-height: 100%
}

body {
    height: 100%;
    font-family: "Helvetica Neue",Helvetica,Arial,sans-serif;
    color: #666;
    background-color: #fff
}

a {
    color: #333;
    text-decoration: none
}

a:hover {
    text-decoration: none
}

ol,ul {
    list-style: none
}

input {
    border: none;
    outline: 0;
    -webkit-appearance: none
}

button {
    border: none;
    outline: 0
}

.fl {
    float: left
}

.fr {
    float: right
}

.pr {
    position: relative
}

.pa {
    position: absolute
}

.pf {
    position: fixed
}

.db {
    display: block
}

.dlb {
    display: inline-block
}

.dl {
    display: inline
}

.dn {
    display: none
}

.t-center {
    text-align: center
}

.clearfix::after,.clearfix::before {
    content: "";
    height: 0;
    line-height: 0;
    display: block;
    visibility: hidden;
    clear: both
}

.v-center {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%);
    -ms-transform: translate(-50%,-50%);
    -moz-transform: translate(-50%,-50%);
    -webkit-transform: translate(-50%,-50%);
    -o-transform: translate(-50%,-50%)
}

.p-middle {
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    -ms-transform: translateY(-50%);
    -moz-transform: translateY(-50%);
    -webkit-transform: translateY(-50%);
    -o-transform: translateY(-50%)
}

.v-body {
    display: inline-block;
    vertical-align: middle
}

.hide {
    display: none
}

@media screen and (max-299px) {
    html {
        font-size: 70px
    }
}

@media screen and (min-300px) {
    html {
        font-size: 80px
    }
}

@media screen and (min-350px) {
    html {
        font-size: 90px
    }
}

@media screen and (min-370px) {
    html {
        font-size: 100px
    }
}

@media screen and (min-375px) {
    html {
        font-size: 26.66666667vw
    }
}

2，