Customizable Web Components UI Library – Shoelace
Shoelace is an open-source, highly customizable, framework-agnostic UI components library for modern web application design.
Frameworks
Bootstrap 5 & Material Design 2.0 UI KIT
A pure JavaScript/CSS UI Kit to help you quickly build Material Design web applications using Bootstrap 5 and 500+ built-in UI components.
Windows 7 CSS Framework – 7.css
A CSS only front-end framework that brings the retro Windows 7 styles to your webpage.
Full-featured CSS Utility Library – PrimeFlex
A lightweight, responsive, feature-rich, utility-first CSS framework for building modern websites.
Create Classic Mac OS Style Interfaces With The System.css Library
A CSS library for creating classic Apple Mac OS style interfaces through HTML and CSS markup.
Fully Styled UI Component Library – PCUI
a fully styled UI component library for Vanilla JavaScript and React apps.
Minimal Clean CSS Design System – Pico.css
Pico.css is a minimal, responsive, semantic, reader-centric design system implemented in pure CSS.
Right-to-left (RTL) Theme For Boostrap 4.x
A full-featured Bootstrap Right-to-left (RTL) theme for Arabic, Aramaic, Azeri, Dhivehi/Maldivian, Hebrew, Kurdish (Sorani), Persian/Farsi, Urdu languages.
Minimal Classless CSS Framework – Simple.css
A lightweight CSS framework (also considered as a CSS reset) that helps developers quickly build a minimal clean looking website.
Customizable Bootstrap 5 Admin Dashboard Framework – AdminKit
A powerful admin framework for building responsive, customizable, professional, cross-browser dashboard & admin panel using Bootstrap 5.