You can download the final CSS files or the source files. If you choose to use SASS and apply your modifications to the framework, you will be able to find all the required files by downloading the source files.
Include the ueyen.min.css or ueyen.css inside the HTML head closing the
</head> tag.
Ready-to-use generated CSS. Link it in your HTML file and you are all set!
Neew more customization & more control? The source file has all the SASS file you need to do so.