h5bp/effeckt.css

Effeckt.css was a CSS library aimed at providing smooth, high-performance animations and transitions for websites and web apps. The project is now archived and no longer maintained, but the code and documentation remain available. The core problem it was trying to solve is that adding visual effects to web pages, such as modal window animations or page transitions, is easy to do badly. Effects implemented poorly can cause stuttering and dropped frames, especially on mobile devices. The project's goal was to collect and provide only effects that could reliably run at 60 frames per second, which is the threshold where motion feels smooth to most people. Any effect that could not meet that standard was explicitly excluded. The library was built on CSS transitions and keyframe animations, particularly ones that trigger hardware acceleration on the device, such as transforms and opacity changes. These properties can often be handled by the device's graphics chip directly, making them much cheaper to animate than properties like width or position. The original ambition included a web-based builder that would let developers pick only the specific effects they needed rather than loading the full library. The project also aimed to define browser support tiers and provide performance testing tools. It was part of the h5bp (HTML5 Boilerplate) GitHub organization, which has historically produced front-end tooling and best-practice starter templates. Since the repository is archived, it should be considered a historical reference rather than something to adopt in new projects.