<div class="wrapper">
  <div class="yellow"></div>
  <div class="red"></div>
  <div class="green"></div>
  <div class="blue"></div>
</div>
/* ONLY FOR CODEPEN */
body {
  margin: 0;
  display: grid;
  place-content: center;
  height: 100vh;
}
/* Main Styles */

.wrapper {
  width: 200px;
  aspect-ratio: 1;
  display: grid;
  grid-template-columns: 1fr 1fr;
}

.yellow,
.blue {
  width: 100%;
  height: 55%;
}

.red,
.green {
  width: 55%;
  height: 100%;
}

.yellow {
  border-radius: 1in 1in 0 7px;
  place-self: end;
  background: #fbbc01;
}

.red {
  border-radius: 7px 1in 1in 0;
  background: #ea4132;
}

.green {
  border-radius: 1in 0 7px 1in;
  place-self: end;
  background: #069e57;
}
.blue {
  border-radius: 0 7px 1in 1in;
  background: #4086f4;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.