background-image: radial-gradient(farthest-side, transparent 100%, black 0),
radial-gradient(circle farthest-side at top left, yellow 50%, transparent 0),
radial-gradient(circle farthest-side at top right, yellow 50%, transparent 0),
radial-gradient(circle farthest-side at bottom right, yellow 50%, transparent 0),
radial-gradient(circle farthest-side at bottom left, yellow 50%, transparent 0),
radial-gradient(dodgerblue, blue);
background-size: 10% 10%;