Advice re: CSS – differences in rendering in Safari and Firefox

I am running a blog using WordPress at https://www.elcreations.org/engloy/photoblog

Having recently switched to a Macbook, I am having problems making my navigation toolbar work properly in Safari compared to Firefox and IE7 (on my old PC): the toolbar at the top right corner is supposed to be displayed as a single line aligned to the top-right corner of the browser window. Safari displays the toolbar split into 2 lines instead.

For ease of viewing (and debugging), I have snipped out the code/CSS and placed them here: https://www.elcreations.org/csstest . The stylesheet is at https://www.elcreations.org/csstest/stylesheet.css

Was wondering whether if any CSS gurus out there can help me with my problem.

Thanks in advance!