Changing the background color of a webpage using puzzles

I’m trying to change the background color of a webpage using puzzles.

If I add the option background-color: directly to the css file it works.

body {
    margin: 0px;
    overflow: hidden;
    background-color: #d24dff;
}

But if I try it using puzzles it doesn’t change any idea what I’m doing wrong? See image of my puzzle below.

Image of puzzle