移动端 rem单位做适配的 媒体查询节点

@media screen and (min-width:300px){html,body,input{font-size:15px}}
@media screen and (min-width:320px){html,body,input{font-size:16px}}
@media screen and (min-width:340px){html,body,input{font-size:17px}}
@media screen and (min-width:360px){html,body,input{font-size:18px}}
@media screen and (min-width:375px){html,body,input{font-size:18.75px}}
@media screen and (min-width:380px){html,body,input{font-size:19px}}
@media screen and (min-width:400px){html,body,input{font-size:20px}}
@media screen and (min-width:414px){html,body,input{font-size:20.7px}}
@media screen and (min-width:420px){html,body,input{font-size:21px}}
@media screen and (min-width:440px){html,body,input{font-size:22px}}
@media screen and (min-width:460px){html,body,input{font-size:23px}}
@media screen and (min-width:480px){html,body,input{font-size:24px}}
@media screen and (min-width:500px){html,body,input{font-size:25px}}
@media screen and (min-width:520px){html,body,input{font-size:26px}}
@media screen and (min-width:540px){html,body,input{font-size:27px}}
@media screen and (min-width:560px){html,body,input{font-size:28px}}
@media screen and (min-width:580px){html,body,input{font-size:29px}}
@media screen and (min-width:600px){html,body,input{font-size:30px}}
@media screen and (min-width:620px){html,body,input{font-size:31px}}
@media screen and (min-width:640px){html,body,input{font-size:32px}}
@media screen and (min-width:660px){html,body,input{font-size:33px}}
@media screen and (min-width:680px){html,body,input{font-size:34px}}
@media screen and (min-width:700px){html,body,input{font-size:35px}}
@media screen and (min-width:720px){html,body,input{font-size:36px}}
@media screen and (min-width:740px){html,body,input{font-size:37px}}
@media screen and (min-width:760px){html,body,input{font-size:38px}}
@media screen and (min-width:780px){html,body,input{font-size:39px}}
@media screen and (min-width:800px){html,body,input{font-size:40px}}
@media screen and (min-width:1024px){html,body,input{font-size:51.2px}}
@media screen and (min-width:1349px){html,body,input{font-size:67.45px}}

也可以使用js来控制：

document.documentElement.style.fontSize = document.documentElement.clientWidth / 3.75 + 'px';//设计稿是375px ，HTML的font-size:100px;

window.onresize = function () {

document.documentElement.style.fontSize = document.documentElement.clientWidth / 3.75 + 'px';

}

通过以上方式使得设备宽度变化时，对应的根元素html的fontsize对应的变化，从而达到rem的相对的值得到改变