message: style(dropdown): add panel anchor/section styles
diff: .Dropdown-panel {
  background-color: var(--background);
  - border-radius: 4px;
  + border-radius: 6px;
  border: solid 1px var(--line-rule-color);
  box-shadow: 4px 4px 12px 4px rgba(0,0,0,0.025);
  min-width: 100%;
  left: 50%;
  transform: translateX(-50%);
  }
  +
  +.Dropdown-panel a {
  + display: block;
  + padding: 0.5em 1em;
  +}
  +
  +@media (hover: hover) {
  + .Dropdown-panel a:hover {
  + background-color: rgba(0, 0, 0, 0.025);
  + }
  +}
  +
  +.Dropdown-panel > section {
  + padding: 0.5em 0;
  +}
  +
  +.Dropdown-panel > section:not(:last-child) {
  + border-bottom: solid 1px var(--line-rule-color);
  +}
  