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>

tests/CmsTest.php

@@ -2232,6 +2232,31 @@ final class CmsTest extends TestCase
         self::assertStringContainsString('@media (max-width:767px){#start-hero{font-size:28px', $html);
     }
 
+    public function testAHeaderCanChangeItsColoursOnceThePageHasScrolled(): void
+    {
+        $this->pages->publish('page-1', $this->pages->saveDraft('page-1', self::styledDocument(), 0), 1);
+        $header = $this->partials->findByKind('header');
+        $document = $header['document'];
+        // Glass over the hero, solid once the reader has moved: the Flatsome transparent header.
+        $document['blocks'][0]['style'] = ['desktop' => ['backgroundColor' => '#ffffff00', 'scrolled' => ['backgroundColor' => '#ffffff', 'color' => '#123456']]];
+        $this->partials->save($header['id'], $document, (int) $header['version']);
+
+        $response = $this->request('/');
+        $html = $response->getContent();
+        self::assertStringContainsString('#area-header{background-color:#ffffff00}', $html);
+        self::assertStringContainsString('#area-header{transition:background-color .3s,color .3s,border-color .3s,box-shadow .3s,opacity .3s}html.is-scrolled #area-header{background-color:#ffffff;color:#123456}', $html);
+        // The small script that marks the scrolled page comes only with such a header, and the
+        // policy opens for it exactly then.
+        self::assertStringContainsString('/assets/scrolled.js?v=', $html);
+        self::assertStringContainsString("script-src 'self'", (string) $response->headers->get('Content-Security-Policy'));
+
+        // Nur Farben, Schatten und Deckkraft dürfen sich beim Scrollen ändern; eine wachsende
+        // Schrift würde die Seite unter dem Finger verschieben.
+        $document['blocks'][0]['style']['desktop']['scrolled'] = ['fontSize' => '40px'];
+        $this->expectException(InvalidDocument::class);
+        $this->partials->save($header['id'], $document, (int) $header['version'] + 1);
+    }
+
     public function testInlineStylesheetIsAllowedByItsOwnHashAndNothingElse(): void
     {
         $this->pages->publish('page-1', $this->pages->saveDraft('page-1', self::styledDocument(), 0), 1);