Bootstrap layout crashes on mobile, how to fix it?

Question

css

Hello!
I am developing a landing page based on bootstrap, the fact is that later adaptive layout is required, so I already decided to do bootstrap, but without adaptation, I rigidly indicated
.container { width: 1200px; }
So I have 6 (six) .col-xs-4 blocks, it turns out they should be in 2 (vde) lines of 3 (three elements), here on a computer and on tablets, everything seems to be okay!
If we open it on the phone, then such a thing happens, I don’t understand why at all (I think something needs to be done with the stand up of the block ...)

What should I do ?? Thanks in advance for your help!
Here is a link to this site, you can see the SITE in detail

Answer 1

or put clearfix after 3 columns

Answer 2

Use flexbox to make all columns the same height. Or place them in two lines (.row) with 3 elements

Answer 3

After the third column put
<div style="clear: both"></div>