body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, avenir next, avenir, segoe ui, helvetica neue, helvetica, Cantarell, Ubuntu, roboto, noto, arial, sans-serif;
  margin: 20vh auto;
  background: #fafaf7;
  color: #313;
}
.container { margin: 20px auto; max-width: 960px; }
h1 {
  font-size: 1.2rem;
  font-weight: bold;
}

.tab {
  display: inline-block;
  margin-inline-end: 0.25rem;
  padding: 0.5rem 1rem;
  border: solid 1px #313;
  border-bottom: none;
  border-top-left-radius: 0.5rem;
  border-top-right-radius: 0.5rem;
}

[role="tabpanel"] {
  padding: 1rem;
  border: solid 1px currentColor;
}