Material Design for Bootstrap 4 - Powerful and free UI KIT for the newest Bootstrap 4 and Material Design
98.css - A design system for building faithful recreations of old UIs
Glassmorphism - A modern CSS UI library based on glassmorphism
Neumorphism UI - Neumorphism inspired UI web components, sections and pages
Themesberg - Start you development with Free and Premium Bootstrap UI Kits, Themes, templates and code snippets
Glass UI Generator - CSS generator for glassmorphism