White Edges around header Picture

Hi all having an issues with a website header picture. Can you please tell me how to get rid of the white above and below the websites top picture. Is there something in the code that I have to modify? Have a attachment of the issue. There is also a Menu, which you can’t see because its white.




Try using this CSS code:

body {
    background-color: black !important;

This code should be placed in a child’s theme stylesheet.css, ideally.
But you can use a Custom CSS plugin or place it inside Dashboard > Appearances > Editor > Style.css but keep in mind that this will get erased if you update the theme.