How can I add gradient to the background

Question

https://sololearn.com/compiler-playground/WtVfk5s4Am1q/?ref=app

Answer 1

By using the background-image attribute correctly:
https://www.w3schools.com/css/css3_gradients.asp

Answer 2

Use the same method I used for the "Explode!" button here:
https://sololearn.com/compiler-playground/WyWX0JXusZb4/?ref=app
This line should help you:
background: linear-gradient(to right, red, blue);