1. 简单入门的rem适配方案，纯CSS实现
html{
font-size:20px;
}
@mediaonlyscreenand(min-width:401px) {
html{
font-size:21.33333333px!important;
}
}
@mediaonlyscreenand(min-width:414px) {
html{
font-size:22.08px!important;
}
}
@mediaonlyscreenand(min-width:480px) {
html{
font-size:25.6px!important;
}
}
body{
font-size:16px;
}
