fix: vertical centering for h2 headers without description in expandable sections (#3993)

Author: Who-is-PS

src/expandable-section/expandable-section-header.tsx

@@ -320,7 +320,12 @@ export const ExpandableSectionHeader = ({
     }
     return (
       <ExpandableHeaderTextWrapper
-        className={clsx(className, wrapperClassName, expanded && styles.expanded)}
+        className={clsx(
+          className,
+          wrapperClassName,
+          expanded && styles.expanded,
+          !expanded && (!headerActions || headerDescription) && styles['wrapper-not-expanded-without-actions']
+        )}
         descriptionId={descriptionId}
         headerDescription={headerDescription}
         headerCounter={headerCounter}

src/expandable-section/styles.scss

@@ -138,6 +138,11 @@ $icon-total-space-medium: calc(#{$icon-width-medium} + #{$icon-margin-left} + #{
       // Equal top and bottom padding so standalone header has vertical symmetry.
       padding-block-end: awsui.$space-container-header-top;
     }
+
+    &.wrapper-not-expanded-without-actions {
+      padding-block-end: calc(#{awsui.$space-container-header-top} + #{awsui.$space-scaled-xxs});
+    }
+
     &.header-deprecated {
       padding-inline-start: container.$header-padding-horizontal;
     }