JSFiddle - React, Tailwind, and code Playground

HTML

<div>кнопка</div>

CSS

* {
  box-sizing: inherit;
}

html {
  box-sizing: border-box;
}


div {
  --w-lg: 30px;
  width: 100px;
  padding: 10px 30px 10px 10px;
  background: linear-gradient(red, red) no-repeat left center / calc(100% - var(--w-lg)) 100%, linear-gradient(to bottom right, red 50%, transparent 51%) no-repeat right center / var(--w-lg) 100%;
}