nostrweb/src/tabs.css

.tabs {
  position: relative;
  min-height: 200px;
}

.tab {
  float: left;
}

.tab > label {
  cursor: pointer;
  font-size: 1.1em;
  padding: .5em 1em;
}

.tab [type=radio] {
  position: absolute;
  height: 0;
  width: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
}

.tab [type=radio] + label {
  outline: 1px solid var(--bgcolor-accent);
}

/*
.tab [type=radio]:focus + label {
  outline: 2px dotted black;
}
*/

.tab [type=radio]:checked ~ label {
  z-index: 2;
  background-color: var(--bgcolor-accent);
  color: var(--fgcolor-accent);
}

.tab [type=radio]:checked ~ label ~ .content {
  z-index: 1;
  opacity: 1;
}

.tab .content {
  position: absolute;
  top: 2.5em;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 1rem 0;
  opacity: 0;
}