<style type="text/css" media="screen">@import "styles.css";</style>
Firefox and Internet Explorer are forgiving about a missing semi-colon, but Safari won't load the stylesheet without it.
And by default Safari has only limited support for tabbing through Web pages (something that's probably pretty important to keyboard users). The default setting will allow you to tab from form field to form field, but you can't focus on links by tabbing. You can enable this behavior (which is behavior I've come to expect from using Firefox and Internet Explorer) by going to the Advanced tab of the Preferences menu and clicking the checkbox that says something like "Press Tab to highlight..."