INSTALL THE MOTHERFUCKING PLUGIN

On theme installation, a dialog for handling the plugin installation should appear. It will lead you to the plugin page and give you an option to enable it after you install it and restart Steam. In case the plugin will stop working, it will give you the option to revert your theme to default.

This theme requires a plugin for the top bar and some other additional elements. The menu bar, links to a game's store page, community hub, etc. and some other things will not be accessible if not installed. Learn to read if you missed this.

Microsoft Office 2007 Styled Theme

Based on a mockup by MondySpartan: https://www.deviantart.com/mondyspartan/art/Steam-Office-2007-Styled-Mockup-1060261068

Other previews

Titlebar is missing

It's going to be available in a separate plugin in the future. It's not released yet because it doesn't start early enough to modify window.open before the main window appears (but works for everything else). The screenshot only includes it so I don't have to take another one.