Fix: some css cleanup (#13891)

src-ui/src/theme.scss

@@ -113,6 +113,7 @@ $form-check-radio-checked-bg-image-dark: url("data:image/svg+xml,%3csvg xmlns='h
   --bs-tertiary-bg: var(--pngx-bg-darker);
   --bs-dark-border-subtle: var(--pngx-bg-darker);
   --bs-border-color-translucent: rgba(0, 0, 0, .175); // override bs
+  --bs-box-shadow-sm: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.15); // slightly darker than bs default
 
   .text-dark, .text-light {
     color: var(--bs-body-color) !important;