message: fix(components): fix CodeGroup tab style
diff: .code-group-nav-tab {
  @include reset.button;
  +
  position: relative;
  min-width: 3rem;
  - border: 0;
  + margin: 0;
  padding: 6px 10px;
  border-top-left-radius: 6px;
  border-top-right-radius: 6px;
  