To become a CSS master, you will need to learn and master the following skills:

HTML and CSS basics: You should be familiar with the basic syntax of HTML and CSS and how they are used to structure and style content on the web.

Responsive design: You should be able to design and build responsive websites that look and function well on a variety of devices, including desktop computers, tablets, and smartphones.

Layout techniques: You should be able to create flexible and advanced layouts using techniques such as floats, flexbox, and grid.

CSS preprocessors: You should be familiar with CSS preprocessors like Sass or Less, which allow you to write more efficient and maintainable CSS code.

CSS frameworks: You should be familiar with popular CSS frameworks like Bootstrap and Foundation, which provide a set of predefined styles and layout components that can be easily customized to fit the needs of your project.

Browser compatibility: You should be aware of browser compatibility issues and know how to troubleshoot and fix them.

Accessibility: You should be familiar with web accessibility standards and know how to create accessible websites that are usable by people with disabilities.

To develop these skills, you can start by learning online through tutorials and online courses, or by working on small projects on your own. As you gain experience and become more comfortable with CSS, you can take on more complex projects and challenges to continue improving your skills.