CSS gradients let you display smooth transitions between two or more specified colors.
CSS defines three types of gradients:
CSS Linear Gradients
To create a linear gradient you must define at least two color stops. Color stops are the colors you want to render smooth transitions among. You can also set a starting point and a direction (or an angle) along with the gradient effect.
background-image: linear-gradient(direction, color-stop1, color-stop2, ...);