<div class="block"></div>

body {
  margin: 0;
}

.block {
  height: 100vh;
  background:
    radial-gradient(circle at 0 0, #f9a413, transparent 70%),
    radial-gradient(circle at 50% 70%, #ff2215, transparent 70%),
    radial-gradient(circle at 100% 100%, #bc6181, transparent 70%),
    radial-gradient(circle at 70% 30%, #12c3d7, transparent 70%),
    radial-gradient(circle at 70% 50%, #5599ee, transparent 70%),
    linear-gradient(#f9a413, #5599ee);
}