设置div根据浏览器自适应高度

因为项目需要设置div的高度在不同的浏览器尺寸上都显示良好，用height：auto是无效的，所以需要用js来解决，

于是设置这个div的id为bannerbig，并用js调用修改、自动改

<script>
//auto adapt clients height for banner which i rename it div id = "bannerbig"    
function refreshSize(){
var totolHeight =  document.documentElement.clientHeight;
var height = totolHeight - 70;
console.log(totolHeight + ' - ' + height);
document.getElementById('bannerbig').style.height = height+'px';
};
refreshSize();
window.onresize = refreshSize;
</script>