I'm writing an article or two about Office Effects Themes and how you can modify them. As an example, I created the Brandwares Flat Theme, which will be of use to designers as is. This theme file gets rid of the bulgy 3-D shapes, glows and hokey shadows of the standard Microsoft themes and relies only on tints, shades and outline variations. You can use this example in 2 ways: as a theme file that you can modify and send as your own, and as an Effects Theme file that can be installed in Office for Windows to provide access to flat shapes in all other themes.
Here you can download the Flat Theme. It's also available on our Downloads page. After downloading, you can open it in PowerPoint, create new font and color themes, apply them, then resave as a new theme. The flat shapes will travel with the theme and be automatically applied to any deck that uses the theme. If you're an Office for Mac user, you'll have to create a font theme using this article: XML Hacking: Font Themes.
The Flat Theme - Specs
There are 7 variants in each row of the the Shape Styles dialog, each showing the dk1 color as a background plus the 6 Accent colors. The first 2 rows feature a 0.5pt outline on the shape in a darker variant of the accent color, with the first row showing a white shape background and the second row the relevant accent color.
The third row is the one I choose most of the time: a flat shape with no outline.
The fourth row has a 50% screened-back background color with black text.
The fills for the 5th and 6th rows are 2 progressively darker shades of the accent colors. The 5th row shows a 50% shade of the color, while the 6th is a two-layer multiplier fill with a 50% shade overlaying a 50% tint. I'll explain these more in the articles to come.
Users of Office 2016 for Windows and for Mac will see an additional group of Presets below the theme shape styles. Except for the stroke weight in row 2, these fills are generated automatically by the program and cannot be modified by XML.
The Flat Theme - Installing as Effects Theme
You can also use the Flat Theme as a new effects theme in Windows versions of Excel, PowerPoint or Word (Office for Mac will display effects themes embedded in a theme or template, but there is no support in the program interface for applying a different effects theme). Then it will appear in the Theme Effects dropdown of Office for Windows along with the standard Microsoft themes. Here are the steps to do that:
Download the Flat Theme from the link above and unzip it.
Change the file name from BrandwaresFlatShapes.thmx to Flat.eftx. The first part of the name can be something other than Flat, but the ending must be .eftx. No other change to the theme file is needed.
Copy the file to the same folder as the Microsoft Theme Effects files: