#grad { background-image: linear-gradient(to bottom right, rgba(255,0,0,0), rgba(255,0,0,1)); }
.gradient { background-image: linear-gradient(angle, color1, color2) // angle: 90deg, color1: red, color2:darkred }
background: linear-gradient(<angle>, color1 color1-stop-at, color2 color2-start-at);