message: update sidebar style to better match new design
diff: @nav-background-color: #1F1F24;
  @nav-scrollbar-color: #4E4E5A;
  -@nav-border-color: #383844;
  +@nav-border-color: #16161B;
  @nav-half-muted-color: #B6BED5;
  @nav-tooltip-color-background: #343740;
  min-width: 300px;
  max-width: 600px;
  max-height: 400px;
  - border: 2px solid #FFF;
  + border: 2px solid #8F8FAB;
  background: @nav-tooltip-color-background;
  border-radius: 10px;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  background: @nav-tooltip-color-background;
  - border-bottom: 1px solid #565C70;
  + border-bottom: 1px solid #1C1F28;
  padding: 8px;
  cursor: pointer;
  transition: background-color 100ms ease-in-out;
  padding-left: 20px;
  border-left: 4px solid transparent;
  border-top: 1px solid transparent;
  - border-bottom: 1px solid #383844;
  + border-bottom: 1px solid @nav-border-color;
  transition: color 100ms ease-in-out, border-left-color 100ms ease-in-out;
  &:focus {
  content: '';
  display: block;
  height: 1px;
  - background: rgba(56, 56, 68, 0.3);
  + background: @nav-border-color;
  position: absolute;
  bottom: 0;
  left: calc(15% + 15px);
  