Widget:BackgroundImage

<style> body {position: relative} body:after {content: ""; opacity: 0.75; top: 0; left: 0; bottom: 0; right: 0; position: absolute; z-index: -1; background: url(""); background-size: contain; background-attachment: fixed; background-repeat: no-repeat; background-position: left top}

1. content, #mw-navigation, .skin-timeless #bodyContent {background: rgba(255, 255, 255, 0.8)}

body.skin-timeless {backgroud: rgba(255, 255, 255, 0.8); opacity: 0.95} </style>