Try to Debugging with Developer Tools:

1. Open Developer Tools: Right-click on the page, select "Inspect" or press F12 on your keyboard.
2. Use the "Elements" Tab: Check the structure of the page. Look for any unwanted divs, containers, or elements that are creating the background or unnecessary padding/margins.
3. Check Styles in the "Styles" Tab: You can also see which CSS properties are being applied to certain elements. Look for padding, margins, or background color that could be coming from an unexpected source.