What Can I Use?
Theme developers often come to the table with their custom toolbox of frameworks, libraries, and development methodologies. A (formerly) frequently asked question from theme developers was, "What can I use with Mura?" In other words, they wanted to know which, if any, of the tools in their toolbox they could pull out and apply to their Mura theme development process.
Use any front-end framework you want.
Most theme developers know that using a front-end framework makes theme development faster and easier. However, there are so many options to pick from. It doesn't matter to Mura whether you're using Bootstrap, Semantic UI, Foundation, or any other front-end framework. Use the one that best suits the needs of your project or personal taste.
In other words ...
Use pretty much anything you want. Period.