<script>!function(n){ var e=n.document, t=e.documentElement, i=750, d=i/100, o="orientationchange"in n?"orientationchange":"resize", a=function(){ var n=t.clientWidth||320;n>750&&(n=750); t.style.fontSize=n/d+"px" }; e.addEventListener&&(n.addEventListener(o,a,!1),e.addEventListener("DOMContentLoaded",a,!1))}(window);</script><style> .aaa{padding: .20rem;}</style></head><body><div id="box"> <div class="aaa">1</div></div></body>