changing background color on Wordpress page

Theme: Wordpress Twenty Seventeen Theme
I want to have a background behind all my pages and the home page to be #fffbbb instead of the white background that comes with the Wordpress Twenty Seventeen theme. I have tried every solution I can find on the Internet and in WPMU forum, but nothing works. What's strange is that using Inspector in the browser, I can see where the background color is: .site-content-contain {
background-color: fffbbb !important; When I change it in the browser, it works great, but it won't work in the child theme's style.css, or in the Appearance/Customize/ Additional CSS. Thanks for any help you can offer.