Animista is a place where you can play with a collection of pre-made CSS animations, tweak them and get only those you will actually use.
When you are building a website with a css framework like Bootstrap, you will only use a part of the framework and unused css styles will be included.
Purgecss removes unused selectors from your css, resulting in smaller files.
"With PurgeCSS, you'll have a hard time generating CSS that isn't under 10kb minified and gzipped." - Tailwindcss docs
Unused CSS finder crawls your website (following all the internal links), analyses all the pages and provides a list of unused css-selectors found in your stylesheets.
Static Site Boilerplate is a free, open-source tool for developers that enables a better workflow for building modern static websites. Automated build processes, a local development server, production minification and optimizations, and the latest standards for static websites.
awsm.css is a very simple CSS library for your pet project, blog or homepage.
CSS Mint is a lightweight (just 3KB gzipped) and fully-responsive open source UI kit built to ease up layout and structuring of your web application. Built on top of normalize.css, it handles cross browser inconsistencies and provides minimalistic CSS components to be used in your application.
Teutonic CSS is a modern CSS framework — versatile, well documented.
CSS Blocks is an ergonomic, component-oriented CSS authoring system that compiles to high-performance stylesheets.
By combining an opinionated authoring system, build-time analysis and rewriting of templates, and a new type of CSS optimizer, css-blocks breathes new power and ease of use into the technologies and best practices that stylesheet developers already know and love.