Halfmoon
Front-end framework with a built-in dark mode
...Halfmoon comes with a built-in, toggleable dark mode, which is one of its most important and defining features. The framework is built entirely using CSS variables (also known as CSS custom properties). There are close to 1,500 CSS variables, which means that almost everything can be customized by overriding a property, making it very easy to theme Halfmoon to fit your brand. Learn more about customization.