Hello,
The majority of the font colors are controlled here:
Template.CSS - Line 803
#s5_register, #s5_login, #s5_nav li a, .S5_parent_subtext, .s5_h3_first, h3.s5_mod_h3, .blog-featured h1, .item-page h1, #s5_date_wrap, #s5_bottom_menu_wrap ul.menu li a, #s5_footer, #s5_footer_module, #s5_footer a, #s5_footer_module a, #s5_button_frame ul li a, #s5_breadcrumb_wrap, #s5_breadcrumb_wrap a, #s5_component_wrap_inner {
color: #ffffff;
}
The rest of the fonts might be called out a bit more specifically. I would suggest using Firebug and hovering over any font element on the site to view where its color properties are inherited from.