tyle>
.container {
  width: 150px;
  height: 150px;
  background: lightblue;
  contain: layout;
}
.hidden {
  content-visibility: hidden;
}
#child {
  width: 50px;
  height: 50px;
  background: lightgreen;
}
.abspos { position: absolute; }
.relpos { position: relative; }
.fixedpos { position: fixed; }
.start { top: 0; left: 0; }
.mid { top: 10px; left: 10px; }
.end { bottom: 0; right: 0; }
.zindex { z-index: 1; }
.small { width: 10px; height: 10px; background: blue; }
.medium { width: 20px; height: 20px; ba