If I’m understanding correctly, You need a <div class="row" before col-sm-4.
EDIT: From your screenshot, I don’t see a container, which you will need. Maybe it is already included but I cant see it.
You need to have <div class="container"> <div class="row"> <div class="col-sm-4">
Try removing the other divs first to see if that fixes your problem, then work on adding others in.
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solved Responsive design not working on mobile