#An angle in pureCSS #https://codepen.io/lehollandaisvolant/pen/NLKGdL div { --angle: 150deg; /* CHANGE THIS VALUE TO THE ANGLE YOU WANT */ } div { height: 300px; width: 600px; overflow: hidden; position: relative; background: crimson; border-radius: 300px 300px 0 0; border: 1px solid crimson; } div::before { height: inherit; width: inherit; position: absolute; content: ""; background-color: white; transform-origin: 50% 100%; transform: rotate(var(--angle)); }