background.css

/*
background: transparent = background: none, and both can be shortened to background:0 0
see: http://stackoverflow.com/questions/20784292/backgroundnone-vs-backgroundtransparent
*/
a {
    background: none;
    background: transparent !important;
}
b {
    background:transparent;
    background:none
}
c {
    background: 0 0
}