Bootstrap col-xs-12 not working for IE

[Alegni]

Hey guys,
I need a little bit help from you

I'm almost done creating a new website for our company. Sadly there is a bug in IE 11 I can't fix myself.
When opened in the mobile version, the IE ignores the col-md-12 and col-xs-12 instruction. It puts all columns next to each other...
The problem doesn't occur in Chrome or Firefox though. Maybe you have an idea how to avoid the problem?
Thanks for your help!

Example how it should look like:

https://i.imgur.com/CtzP4Us.jpg

You get the Code here:

https://gist.github.com/alegni/90a72...09db51f841b6fa


Problem Solved. Just added text-align to the blog CSS and erased all col-terms except for col-md-4 ...