<a href="#">TIKLA</a>
<span>W3TR</span>

a{display: inline-block; background: #00FF99; padding:20px; border-bottom:4px solid #00CC00; color:#00CC99; text-decoration:none; margin-bottom:20px;}
span{display:block;}

$("a").click(function(){
 $("span").css("font-size","30px");
});