JSFiddle - React, Tailwind, and code Playground

HTML

<div class="crossed"></div>

CSS

.crossed {
    width: 100px;
    height: 100px;
    background: 
       linear-gradient(to top left,
           rgba(0,0,0,0) 0%,
           rgba(0,0,0,0) calc(50% - 0.8px),
           rgba(0,0,0,1) 50%,
           rgba(0,0,0,0) calc(50% + 0.8px),
           rgba(0,0,0,0) 100%),
       linear-gradient(to top right,
           rgba(0,0,0,0) 0%,
           rgba(0,0,0,0) calc(50% - 0.8px),
           rgba(0,0,0,1) 50%,
           rgba(0,0,0,0) calc(50% + 0.8px),
           rgba(0,0,0,0) 100%);
}