If you style your content using CSS, you need to ensure the corresponding classes are transferred when you use a different WordPress theme. For example, if you have created custom classes to style the tables of a particular page on your website, these classes would have to be copied from your old stylesheet to the new one.
Marcel Brinkkemper has addressed this problem with his plugin ‘Lazyest Stylesheet‘. It creates two additional stylesheets for you: one or your desktop website and another for the mobile version of your site.
As long as the plugin is activated, you can use the classes entered in these stylesheets with any design you use.
Lazyest Stylesheet is a very simple plugin but it’s also a very useful one if you use CSS classes in your design that you want to be usable with any theme.