Any application, including Open edX, can be loosely divided into two parts: the user interface (“how it looks”), and the application logic (“how it works”). For example, when considering a multiple choice problem in Open edX, the user interface consists of how the options are laid out on the page, how the option selectors look, how the submit button is labelled, what sort of fonts and colors are used to display the text, and so on. The application logic consists of how Open edX determines if the student’s answer is correct or incorrect, and how it records that information to be displayed in the future.
Theming consists of changing the user interface without changing the application logic. When setting up an Open edX website, the website operator often wants to use their own logo, modify the color scheme, change links in the header and footer for SEO (search engine optimization) purposes, and so on. However, although the user interface may look different, the application logic must remain the same so that Open edX continues to work properly. A well-designed theme preserves the general layout and structure of the user interface, so that users of the website still find it familiar and easy to use. Be careful about making sweeping changes to the user interface without warning: your users will be very confused!
From a technical perspective, theming consists of overriding core templates and core assets with themed templates and themed assets.
The Open edX platform already comes with a set of templates and assets that are used in the default user interface; these are known as core templates and core assets. To create a theme, you simply replace some or all of these core templates with your own themed templates, as well as replacing some or all of the core assets with your own themed assets.
There is no limit to the number of themes you can have installed on your Open edX servers, but only one can be active at a time. Multitenancy (the ability to have different themes active in different contexts) is not yet supported.
Currently, the LMS and Studio can be themed. All other parts of the Open edX software do not yet support theming. This includes Insights, XBlocks, certificates, notification emails, and so on.
Within the LMS and Studio, only a few templates and assets are currently supported for theming. All templates and assets can be themed, but unsupported templates and assets may be renamed or used differently in the future, and these changes may occur without notice. The following pages describe the currently supported templates and assets.