<div class="box"></div>
.box {
display: inline-block;
width: 300px;
aspect-ratio: 1;
margin: 10px;
border: 2px solid red;
background: repeating-conic-gradient(#000 0 10%,#0000 0 20%)
}
This Pen doesn't use any external CSS resources.
This Pen doesn't use any external JavaScript resources.