Well since Safari 3 Win came out, I feel pretty good about writing for Safari Mac. I know that S3W isn't the perfect testing bed for for Safari in general, but it's fairly good. And I have noticed that things can usually be worked out for S3W. On those rare occasions where I get to view the results on a 'real' Safari browser, they have worked out.

I think the border thing with the text input is because the default behavior onfocus in Safari for a text input is for the border to highlight. If you set a border in the stylesheet, this still happens, but somehow just doing so gives you control of the background color. It would probably also work for a background image, but I haven't tested that.