ميدياويكي:Gadget-hdedit.css

 h1 span.mw-headline:hover,
 h2 span.mw-headline:hover,
 h3 span.mw-headline:hover,
 h4 span.mw-headline:hover,
 h5 span.mw-headline:hover,
 h6 span.mw-headline:hover { 
 	border-bottom: solid 1px #0645ad;
 }