style: apply about margin fixup to all header types

src/styles.css

@@ -67,7 +67,7 @@ body {
 Header elements which are the first child of the about content container shouldn't have the default Ant Design top
 margin
  */
-.about-content h2:first-child, h3:first-child {
+.about-content h1:first-child, h2:first-child, h3:first-child, h4:first-child, h5:first-child, h6:first-child {
   margin-top: 0;
 }