JSFiddle - React, Tailwind, and code Playground

HTML

<div id="main">
    <div class="box curves top"></div>
    <div class="box curves green"></div>
    <div class="box curves red"></div>
    <div class="box curves yellow"></div>
</div>

CSS

body{
  background-color:black;
}

#main {
    position: absolute;
    top: 50%;
    left: 50%;
    margin: -15% 0 0 -15%;
    height: 0px;
    width: 30%;
    padding-top: 30%;
    overflow: visible;
    -webkit-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
}
.box {
    display: block;
    width: 45%;
    height: 45%;
    position: absolute;
}

.curves{
  border : 2px solid white;
  border-radius : 20px;
}

.top { 
    top: 0;
    left: 0;
}
.green {
    top: 0;
    right: 0;
}
.red {
    bottom: 0;
    right: 0;
}
.yellow {
    bottom: 0;
    left: 0;
}