I was tinkering with custom grid and wanted to see how other people have created their grid-systems. Since twitter's bootstrap seemed to be so popular i've looked at its code. Now i wonder why are they using floats? I would use display: inline-block; html elements have either display: inline; or display: block; i would try to avoid floats. But for some reason bootstrap creators decided to use floats. first i was thinking they used them to have backward compatibility since ie6 does not support display: inline-block; and ie7 supports it only on elements with display: inline; by default. But ie6 more or less out of the game and since they use micro clearfix hack which uses *zoom: 1; to target ie6+ IMO they could replicate the same display: inline-block; with *display: inline; *zoom: 1; So the final Question Why Floats Over Display Inline Block? Are there any issues they tried to solve i didn't mentioned above?