Sync styleguide 2026.05.18.1

public/assets/styleguide.upstream.css

@@ -2563,7 +2563,6 @@ section + section {
   display: flex;
   flex-direction: column;
   width: 100%;
-  background: var(--surface-form-preview);
   min-width: min(
     100%,
     calc(var(--layout-form-sections-label-column-width) + var(--spacing-small) + var(--layout-input-field-desktop-width))