@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document domain("login.yahoo.com") {

 div[id="yregtxt"],
 div[id="yregft"],
 div[id="popup"],
 a[class="header"],
 div[class="yregdlisu"],
 div[class="second yregbx"]
 { display: none !important; }

 #yreglg { float: inherit !important; }
 #yregwp { width: 300px !important;
 margin-top: 50px !important; }
}