I tried just inheriting
@import "bootstrap.less";
.span2 { .col-md-2; }
but that gives me
Running "less:dev" (less) task
>> NameError: .col-md-2 is undefined in src\bs2compat.less on line 9, column 10:
>> 8
>> 9 .span2 { .col-md-2; }
>> 10
I'm guessing it has something to do with how Bootstrap defines the .col-__-X classes (https://github.com/twbs/bootstrap/blob/master/less/grid.less#L48 and https://github.com/twbs/bootstrap/blob/master/less/mixins.less#L790), which I must honestly say I can't quite wrap my head around..
I'm preferably looking for ways that don't change the Bootstrap source code (so can avoid maintaining a private Bootstrap fork)..?