#active{background:linear-gradient(135deg,transparent 10px,#00e7a6 0) top left,linear-gradient(225deg,transparent 10px,#00e7a6 0) top right,linear-gradient(315deg,transparent 10px,#00e7a6 0) bottom right,linear-gradient(45deg,transparent 10px,#00e7a6 0) bottom left;background-size:50% 50%;background-repeat:no-repeat}