Add cover styling for petition pages

Add responsive cover image styling with object-fit and height
constraints
Adjust cover image positioning to focus on bottom of image
Update HTML class to include cover styling context

content/underskriftskampanje/medisinsk-cannabis-pa-resept/styles.css

@@ -8,6 +8,11 @@ article > h4 {
     color: oklch(from var(--color-grey) l c h / calc(l + 0.35));
 }
 
+
+main article .cover img {
+    object-position: center 100%; /* adjustable focus point */
+}
+
 /* Button */
 .button--petition {
   background-color: var(--color-green);