Restyle Workflow Graph (#36912)

Follow GitHub's style and fine tune colors & layouts.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

web_src/css/base.css

@@ -808,9 +808,7 @@ table th[data-sortt-desc] .svg {
 
 .btn,
 .ui.ui.dropdown,
-.flex-text-inline,
-.flex-text-inline > a,
-.flex-text-inline > span {
+.flex-text-inline {
   display: inline-flex;
   align-items: center;
   gap: var(--gap-inline);