Heads up! this post was created when Microthemer was at version 2. The current version is 7. Some references to the interface may be out of date.
Microthemer allows you to reuse your own design settings or make use of someone else’s via importable/exportable design packs. A design pack contains folders, selectors, hand-coded CSS, and background images that someone previously created using Microthemer. Design packs come in two types: skins and scaffolds.
Skins contain new styles that will change the appearance of a theme or plugin. A skin that targets a particular theme is referred to as a Theme Skin, whereas a skin that targets the content generated by a plugin is referred to as a Plugin Skin. For example, you might be using the Contact Form 7 plugin. By applying a ‘Plugin Skin’ for Contact Form 7 (which you can download from themeover.com), you can instantly style the plugin without having to do anything other than import the design pack.
Unlike skins, scaffolds don’t actually change the appearance of anything. Their purpose is to ‘scaffold your own design process. Scaffolds are helpful because they contain numerous selectors that target the HTML elements of a specific theme or plugin. But these selectors don’t contain any new style rules. They are ready for you to input your own styles. It’s a bit like being handed a colouring in book. Scaffolds remove some labour and time from the design process and because they have been made by experienced CSS gurus they also give you some solid “rails” to keep you on track. Themeover provides Theme Scaffolds and Plugin Scaffolds.
Scaffolds are optional of course. Microthemer’s double-click to edit feature means you don’t need to rely on scaffolds being available for the particular theme or plugin you would like to customize. And even if you do use a scaffold, you are not constrained to use only the selectors provided. You are free to “go off the rails”.
Read about Installing and Importing Design Packs