<div class="box">
  <sh></sh>
</div>

.box {
  --r: 40px;
  
  width: 150px;
  height: 150px;
  border: 2px solid green;
  border-radius: var(--r);
  position: relative;
  transform: translate(0);
  transform-style: preserve-3d;
}

.box sh {
  position: absolute;
  inset: -150px;
  border: 150px solid red;
  background: lightblue;
  border-radius: calc(150px + var(--r));
  transform: translateZ(-1px);
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-content: center;
}