Making page all one color

How do I make my page all one color. I’ve changed everything to black on my Sydney theme page, except for text and still have a white border around my Gallery. Here’s a link to the page: Thanks for any help.


Please add these CSS code into: Customize > additional CSS.

.page-wrap .content-wrapper {
    background-color: black;


Thank you, that worked great. I’m just surprised there isn’t a color button for that. Seems there is for just about everything else. Thanks again.