IE5/Mac and standards

I don’t know why the gurus keep heaping praise on IE5/Mac’s “standards-compliance.” One must wonder what “standard” they had in mind when the browser absolutely insists on "text-align: left" even while the <div> class clearly says "text-align: center". Bottom-line is that many pages break in IE5/Mac and only there, when I know that my CSS is up to par. Mozilla gives me no such grief. Grrr.