Spotlight

<div></div>
<style>
  body {
    background: #e3516e;
    display: grid;
    place-content: start end;
    margin: 0;
  }
  div {
    width: 150px;
    height: 150px;
    background: #d9d9d9;
  }

  div::after {
    content: '';
    width: 150px;
    height: 250px;
    background: #d9d9d9;
    position: absolute;

    translate: -15px -35px;
    border-radius: 0 0 100px 100px;
    rotate: 45deg;
  }
</style>