移动端适配rem&&媒体查询

第一种：根元素为100px，再按照750设计稿转化成vw单位，这样只要按照设计稿的单位/2便可。若是是小程序，不须要除以2。

html{
    font-size: 26.66vw;  //移动端适配 这里使用rem+vw方案 省去媒体查询  
}

第二种：媒体查询 按照750设计稿，根元素是100px，兼容性比较好。

html {
    font-size: 625%;  /*100 ÷ 16 × 100% = 625%*/
}
@media screen and (device-width: 320px) and (device-height: 568px) and (-webkit-device-pixel-ratio: 2){
    html {  }
}
@media screen and (min-width:360px) and (max-width:374px) and (orientation:portrait) {
    html { font-size: 703%; }
}
@media screen and (min-width:375px) and (max-width:383px) and (orientation:portrait) {
    html { font-size: 732.4%; }
}
@media screen and (min-width:384px) and (max-width:399px) and (orientation:portrait) {
    html { font-size: 750%; }
}
@media screen and (min-width:400px) and (max-width:413px) and (orientation:portrait) {
    html { font-size: 781.25%; }
}
@media screen and (min-width:414px) and (max-width:431px) and (orientation:portrait){
    html { font-size: 808.6%; }
}
@media screen and (min-width:432px) and (max-width:479px) and (orientation:portrait){
    html { font-size: 843.75%; }
}