message: actually the border color helps a lot on the dark theme in terms of making the popup differentiable from the background color.
diff: @@ -87,6 +87,9 @@ select {
  font-size: 13px;
  border-radius: 4px;
  box-shadow: 1px 1px 5px var(--vscode-widget-shadow);
  + border-color: var(--vscode-dropdown-border);
  + border-width: 1px;
  + border-style: solid;
  }
  .tooltip-arrow,
  