message: fix(md-enhance): fix code-group tab
diff: .code-group-nav {
  display: flex;
  - /* 2 * margin + border-radius of <pre> tag */
  - margin: 0.85rem 0 calc(-1.7rem - 7px);
  - padding: 0 0 calc(1.7rem - 7px);
  + margin: 0.85rem 0 -0.85rem;
  + padding: 0;
  border-top-left-radius: 6px;
  border-top-right-radius: 6px;
  background-color: var(--code-group-nav-bg-color, #3a404c);
  