tinyfly/bootstrap — comment on commit 518955e3d1c89c4acb489f777d6891f785f90f73
File: bootstrap.css line 2571
By tinyfly:

On second look, using `*=` allows for multiple classes on an element in any order. If we used `^=` then if you had multiple classes then the `span` one would half to be the first in the list. Thats a bit too restrictive and error prone.