base skin css get warnings from CSSLint

It has been the issue ever since the very beginning.  if some CSS validation tool ,like CSSLint is used, It will throw warnings again the base skin style, for example :

CSSLint Warning Don't use adjoining classes .at line 10 col 68
CSSLint Warning Don't use IDs in selectors .at line 10 col 1

I was wondering if this issue should be brought into any attentions.