只写js部分,其他的样式省略了,多请大家谅解。。。,有写的不好的请各路大神指正,感谢
<script>
var nav =document.getElementById("nav");
document.onscroll = function(){
var h = document.body.scrollTop || document.documentElement.scrollTop;
if(h>168){
nav.style.top =0;
nav.style.position = "fixed";
}else{
nav.style.position = "static";
}
}
</script>