Sharp edge with HTML and CSS only -

it's more easy explain i'm trying achieve showing example.

    div{          width:100px;height:100px;          border:3px solid #900;          border-radius:0px 0px 140px 0px;      }

          <div></div>

i want draw sharp, direct line(point-to-point) between top-right , bottom-left corners. how do border-radius?

are trying make right triangle border?

div {    width: 0;    height: 0;    border-style: solid;    border-width: 200px 200px 0 0;    border-color: #007bff transparent transparent transparent;    position: relative;  }    div::before {    width: 0;    height: 0;    border-style: solid;    border-width: 182px 182px 0 0;    border-color: white transparent transparent transparent;    content: '';    display: block;    top: -195px;    left: 5px;    position: absolute;    z-index: 2;  }

<div></div>

admittedly, is bit of wacky way you're after, requires precise manipulation correct - though it's 1 way, using css, achieve goal.