.round {
background:
radial-gradient(circle at 0 100%, rgba(204,0,0,0) 14px, #c00 15px),
radial-gradient(circle at 100% 100%, rgba(204,0,0,0) 14px, #c00 15px),
radial-gradient(circle at 100% 0, rgba(204,0,0,0) 14px, #c00 15px),
radial-gradient(circle at 0 0, rgba(204,0,0,0) 14px, #c00 15px);
background-position: bottom left, bottom right, top right, top left;
background-size: 50% 50%;
background-repeat: no-repeat;
padding: 14px;
}