I have not found this to be true at all. It's far less than 99%, and would require double checking all your work in IE11 to make sure it works. I tried some bas

I have not found this to be true at all. It's far less than 99%, and would require double checking all your work in IE11 to make sure it works. I tried some basic layouts and found that a lot of unexpected things occurred. If you're supporting IE11, CSS grid isn't worth it.