message: Restyle tabs.
diff: }
  .tab-header {
  - background-color: var(--black-color);
  opacity: 0.3;
  position: relative;
  height: var(--title-bar-height);
  - flex: auto;
  + width: 200px;
  display: inline-block;
  text-align: center;
  padding-top: 2px;
  }
  .tab-header:hover {
  - background-color: var(--background-color);
  + background-color: var(--black-color);
  opacity: 1;
  }
  