how to make background color from bright blue to dark blue using css/html/js

im trying to make my website background start as a light blue background color and end up with slightly darker blue.

is there a way to code it? or should i put an image as the background(if no other option) ?

here is the image with the exact colors i want my background to have :

please ignore the clouds in the image, and check the colors only.

>Solution :

Use a gradient

main {
  height: 100vh;
  background: linear-gradient(skyblue, darkblue);
}

<main></main>