Less

vs

Water.css

Sass stands for syntactically awesome style sheets and is a mature, stable, and powerful CSS extension language. With Sass, web designers can work smarter and faster with CSS by providing a more elegant syntax for CSS and implementing various features that are useful for creating manageable stylesheets at scale. Some of these features include adding nested rules, variables, mixins, selector inheritance, and more. Sass has been active development since 2006, and continues to provide value to the web designer community until this day. It's released free and open-source under the MIT license.

A free and open-source HTML and CSS framework dedicated to responsive and mobile-first frontend web development. With Bootstrap developers can get up and running fast without writing boilerplate HTML and CSS. Bootstrap comes packed with design templates and standards for buttons, forms, navigation, typography and interface components. The framework also provides extra interactive JavaScript extensions written specifically for Bootstrap.

Tailwind CSS is a customizable, low-level HTML & CSS framework. With Tailwind CSS you can create unique UIs without having to write any CSS. The framework comes with pre-written CSS classes that you can add to HTML elements to build bespoke UI components, your way.