JSFiddle - React, Tailwind, and code Playground
HTML
<div id="test"></div>
CSS
#test {
width: 200px;
height: 200px;
background: black;
clip-path: polygon(50% 0, 100% 50%, 50% 100%, 0 50%);
position: relative;
filter: blur(15px);
}
#test:after {
content: "";
display: block;
position: absolute;
top: 0px;
left: 0px;
width: 100%;
height: 100%;
background: white;
clip-path: inherit;
}