Improve "look and feel" of tabs to make it clearer where they start/end (#26828)

* improve "look and feel" of tabs to make it clearer where they start/end

* add border-radius to tab-pane

* remove the .td-content .hightlight margin when inside the tab-content

Author: lsq645599166

assets/scss/_base.scss

@@ -869,3 +869,22 @@ body.td-documentation {
       display: none;
     }
 }
+
+// nav-tabs and tab-content
+.nav-tabs {
+  border-bottom: none !important;
+}
+
+.td-content .tab-content .highlight {
+  margin: 0;
+}
+
+.tab-pane {
+  border-radius: 0.25rem;
+  padding: 0 16px 16px;
+
+  border: 1px solid #dee2e6;
+  &:first-of-type.active {
+    border-top-left-radius: 0;
+  }
+}