petty

inflexible, ironbound, obdurate, obstinate, rigid, set, stubborn, unyielding, wrongheaded

bigoted, intolerant

biased, jaundiced, one-sided, partial, partisan, prejudiced

brass bound, hidebound, old-fashioned, reactionary, stodgy, straitlaced (or straightlaced), stuffy

dogmatic (also dogmatical), opinionated

inferior, mean

imperceptible, inappreciable

little, puny, tiny

hairsplitting, nitpicking, pettifogging, quibbling

one-horse, small-fry, two-bit