Update yamm.less
Update yamm.less

Bootstrap already provides this :

https://github.com/twbs/bootstrap/blob/master/dist/css/bootstrap.css#L3226
16nsk/yamm3,danielchikaka/yamm3,kitsguru/yamm3,geedmo/yamm3,carabina/yamm3,16nsk/yamm3,lrealdi/yamm3,2braincells2go/yamm3,Burick/yamm3,janusnic/yamm3,danielchikaka/yamm3,geedmo/yamm3,kitsguru/yamm3,janusnic/yamm3,paulschwarz/yamm3,lrealdi/yamm3,carabina/yamm3,b-cuts/yamm3,b-cuts/yamm3,paulschwarz/yamm3,2braincells2go/yamm3,Burick/yamm3