<div id="id" contenteditable="true" class="aspect-ratio-box">9</div>

html, body{
  background: #000;
}

.aspect-ratio-box {
  background: yellow;
  position: absolute;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 100%;
  padding: 5px;
  min-width: 1.2em;
  
  box-shadow: 0 0 10px 0 yellow;
}
.aspect-ratio-box::before {
  content: "";
  width: 1px;
  margin-left: -1px;
  float: left;
  height: 0;
  padding-top: 100%;
}
.aspect-ratio-box::after { /* to clear float */
  content: "";
  display: table;
  clear: both;
}

setTimeout(()=>id.focus(), 1000)