Background-color and Background-image not shown in IE and Edge

I want to put a background-image to the site https://maler-schweis.de but in Internet Explorer and Edge Browser and Safari it is not visible. (Also changes in background color don′t appear in these browsers) What do I have to change? Page is in maintenance mode. If you need to get access to answer my question let me know.
Thx, Jennifer

• This topic was modified 5 years, 9 months ago by Obersack.

The page I need help with: [log in to see the link]