Make sure that rich-text has spacing and margin. DDFFORM-5

It worked in Storybook, but not in Drupal.
That is because Storybook adds its own wrapper, which made it appear
correct.

src/stories/Library/rich-text/rich-text.scss

@@ -6,6 +6,9 @@
 
   // Setting a max-width to increase readability for sentences.
   max-width: $layout__max-width--text;
+  margin: auto;
+  padding-left: $layout__page-padding;
+  padding-right: $layout__page-padding;
 
   a {
     @extend %text-inline-link;

src/styles/scss/tools/variables.layout.scss

@@ -3,3 +3,7 @@ $layout__max-width--small: 768px;
 $layout__max-width--large: 1440px;
 
 $layout__max-width--text: 780px;
+
+// Some elements should not go out to the edge of the screen on small screens.
+// This is the padding that is always shown on the left and right.
+$layout__page-padding: $s-xl;