So my understanding as per the documentation was
xs = small like phones
sm = ipads and other tablets
md = smaller laptops
lg = big laptops and big desktops
<div class="col-xs-12 col-md-4 col-lg-3">
<div class="thumbnail"></div>
......
</div>
What I expect is that on my mobile phone the item will take the full width with "gutters" on either side.
On tablets(sm) I expect it to pick the previous declarion of xs so it should take the whole 12 cols. Since I didn't specify anything of "sm"
On laptops(md) I expect three items.
and on larger (lg) screens I four items per row.
The method I am using to test for responsiveness is simply adjusting my browser. What happens when I shrink the window is that my items do end up becoming one item per row when its at its smallest (xs and sm) but it overflows I can't see the entire item.
What am I doing wrong, did I misunderstand the theory behind the grid system?