<div class="wrapper" style="position: relative; width: 100vw; height: 100vh; background-color: red;">
<div class="aa"></div>
啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊
</div>
.aa{
background:hsla(0,0%,100%,.25) border-box;
width: 100vw;
height: 100vh;
position: absolute;
top: 0;
left: 0;
z-index: 100;
-webkit-filter:blur(20px);
filter:blur(20px);
}