Even when the w3c validator finds no errors at all in your page (which is a quite rare happening) this can happen, since not all browsers support all html and all css.
But that 'sometimes' is strange. The behavior of a browser should be consistent, that is, always the same on the same page.
my website is different in both browsers in chrome it seems fine but in safari sometimes it goes crazy and missy why is that
website: اخبار التكنولوجيا