TopCoat – Modern UI Library For Web Apps
The elements use clean, standards-compliant HTML-CSS and all of them are created with responsive layouts in mind.
The library provides 2 style guides, one for desktop and the other for mobile where all elements are showcased inside these guides.
Using TopCoat is very straightforward, just include the CSS file, use its HTML structure and customize however wanted.
For anyone not using any front-end frameworks or looking to improve their frameworks, TopCoat is a good resource to get started quickly while developing web apps.