媒介查询和字体自动调整

html{
    font-size:10px;
    
}
@media only screen and (min-321px ) and (max-375px) {
    html{font-size:11px;}
}
@media only screen and (min-376px ) and (max-414px) {
    html{font-size:12px;}
}
@media only screen and (min-415px ) and (max-639px) {
    html{font-size:15px;}
}
@media only screen and (min-640px ) and (max-719px) {
    html{font-size:20px;}
}
@media only screen and (min-720px ) and (max-749px) {
    html{font-size:22.5px;}
}
@media only screen and (min-750px ) and (max-799px) {
    html{font-size:23.5px;}
}
@media only screen and (min-800px ){
    html{font-size:25px;}
}