Degradado radial en CSS
.gh-fairbilling { background: radial-gradient(circle farthest-corner at right bottom,#91c6ff,#648ecc 10%,#4667ae 20%,#3242a0 27%,#38228f 35%,#2d1470 50%,#310c4f 63%,#220326 93%,#000); }