MediaWiki:Activity.css/Activity 19.css

body.page-Special_WikiActivity { background-attachment: fixed; background-position: center; background-repeat: no-repeat; background-size: 100% auto; background: url("http://vignette4.wikia.nocookie.net/sonako/images/8/84/Activity_09_Background.jpg/revision/latest?cb=20151212084800"); }