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

@-moz-document domain("twitter.com") {

.component, 
body,
.main-tweet-box,
.tweet-box h2,
.main-tweet-box div,
.main-tweet-box div div,
.main-tweet-box div div a
{
  font-family: Arial !important;
}

}