グラデーションとrgbaの壁background: -webkit-gradient(linear, left top,right top, from(#f00), color-stop(0.4,rgba(0,0,0,0)), color-stop(0.6,rgba(0,0,0,0)), to(#f00));background: -webkit-gradient(radial, center center, 20, center center, 70, from(rgba(0,0,0,0)), color-stop(0.5,#f00), to(rgba(0,0,0,0)))