.bg-size-cover{background-size:cover}
.bg-size-contain{background-size:contain}

.bg-no-repeat{background-repeat:no-repeat}
.bg-repeat-x{background-repeat:repeat-x}
.bg-repeat-y{background-repeat:repeat-y}

.bg-top{background-position:top}
.bg-bottom{background-position:bottom}
.bg-left{background-position:left}
.bg-right{background-position:right}
.bg-center{background-position:center}