There are several types of gradients, this one creates one in a circular fashion
1300px is the radius of the gradient
The gradient starts 80 from the left side of the object this is applied to, and 100px down from the top.
The last two values are colors, this one is light teal to transparent
background: radial-gradient(circle 1300px at 80% 100px, #c9eded, transparent);
background-repeat:no-repeat;