несколько радиальных градиентных CSS

background:
    radial-gradient(circle at top left, transparent 15px, #58a 0) top left,
    radial-gradient(circle at top right, transparent 15px, #58a 0) top right,
    radial-gradient(circle at bottom right, transparent 15px, #58a 0) bottom right,
    radial-gradient(circle at bottom left, transparent 15px, #58a 0) bottom left;
background-size: 50% 50%;
background-repeat: no-repeat;
T-DaMER