rem适配的两种方式（css媒体查询和js控制）

css媒体查询：（根字体大小100px，如果10px大小，写成0.1rem）
html {
font-size : 100px;
}

@media only screen and (min-width: 320px) and (max-width: 479px){
html {
font-size: 42.67px !important;
}
}
@media only screen and (min-width: 480px) and (max-width: 639px){
html {
font-size: 64px !important;
}
}
@media only screen and (min-width: 640px) and (max-width: 749px){
html {
font-size: 85.34px !important;
}
}

@media only screen and (min-width: 750px) and (max-width: 959px){
html {
font-size: 100px !important;
}
}
@media only screen and (min-width: 960px) and (max-width: 1241px){
html {
font-size: 128px !important;
}
}

@media only screen and (min-width: 1242px){
html {
font-size: 165.6px !important;
}
}

js控制（zepto / jQuery）（根字体大小100px，如果10px大小，写成0.1rem）
function setFont() {
let window_width = window.innerWidth;
let font_size = parseFloat(window_width / 3.75);
$(‘html’).css(‘font-size’, font_size);
}

$(window).on(‘resize’, function () {
setFont();
});