message: fix(theme): fix sidebar z-index
diff: // NOTE: Compatible with Android Wechat
  // inset-inline-start: 0;
  left: 0;
  - z-index: 125;
  overflow-y: auto;
  // on mobile
  @media (max-width: hope-config.$tablet) {
  + z-index: 125;
  +
  // a collapsed sidebar should not have box shadow
  box-shadow: none;
  