Why doesn't IE11 load the background with CSS?

Question

css

Here is the screenshot

Answer 1

для main нужно прописать display: block;
ИЕ не распознаёт теги html5.

Answer 2

It’s hard to guess without code, so just random versions:
0. Carefully check the url (sometimes a stupid mistake sits in one character)
1. Try to specify cover as a separate property
2. Check doctype (did IE switch to some kind of compatibility mode? )