Give the header scrolled colours and equal card heights in 1.11.1

Cards, quotes and call-to-action bands side by side in a row are equal in
height again: the stacking margin meant for a column no longer applies inside
a row. The header can carry a second set of colours for the scrolled page,
the Flatsome transparent header: a "scrolled" state next to "hover", limited
to colours, shadow and opacity, marked by a small script only where it is
used, plus a setting that lets the header float over the first section.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/Content/StyleSchema.php

@@ -219,6 +219,16 @@ final class StyleSchema
         return array_keys(array_filter(self::properties(), static fn (array $p): bool => $p['hover'] ?? false));
     }
 
+    /**
+     * Properties that may also carry a value for the scrolled page - the Flatsome transparent
+     * header that turns solid once the reader has scrolled. Colours, shadow and opacity only:
+     * a header that changes size while scrolling would push the page around under the finger.
+     */
+    public static function scrollable(): array
+    {
+        return ['backgroundColor', 'color', 'borderColor', 'shadowColor', 'opacity'];
+    }
+
     public static function sides(): array
     {
         return ['top' => 'Oben', 'right' => 'Rechts', 'bottom' => 'Unten', 'left' => 'Links'];