Changes

<p style="font-size:1.125em;line-height:1.5" >Those mockups look amazing. The only things i would do now, is make the back button on the windows more like the one that you made in the Mac version, to keep consistency. Also, give the address box a bigger height and font, maybe 28px for the height and 16px for the font. Having the favicon on both the tab and the address box is redundant, so a simpler design would be to just show it just in one area. The last ones with the darker background look significantly better than the lighter design.