JSFiddle - React, Tailwind, and code Playground

HTML

<div class="item item-1"></div>

<div class="item item-2"></div>

CSS

@import url('https://fonts.googleapis.com/css2?family=Neucha&display=swap');

:root {
  --color: #f2ad1a;
}
* {
  box-sizing: inherit;
}

html {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Neucha', cursive;
}
.item {
  height: 200px;
}
.item-1 {
  background: var(--color);
  border-radius: 0 0 30px 0;
}
.item-2 {
  position: relative;
  background: #fff;
  border-radius: 30px 0 0 0;
}
.item-2::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  display: block;
  width: 50px;
  height: 50px;
  background: var(--color);
  z-index: -1;
}