Find out the following from black.css

div#video-share-links > form > div > label {
background-color:#FFFFAA;
margin-left:1px;
padding:2px;
width:180px;
}


and Replace with below code

div#video-share-links > form > div > label {
background-color:#000000;
margin-left:1px;
padding:2px;
width:180px;
}