A session on CSS, or Cascading Style Sheets, would typically cover the basics of how to use CSS to style and format HTML documents. This might include an overview of the different ways to apply styles to HTML elements, such as using inline styles, embedded styles, or external style sheets. The session might also cover different types of CSS selectors, including element selectors, class selectors, and ID selectors, and how to use them to target specific elements in a document.

Other topics that might be covered in a session on CSS could include how to use CSS to control the layout and positioning of elements on a page, how to work with different types of units in CSS (such as pixels, ems, and percentages), and how to use CSS to create responsive designs that adapt to different screen sizes and devices.

Overall, a session on CSS would aim to provide a solid foundation in the basics of CSS styling and layout, with practical examples and exercises to help participants gain hands-on experience working with CSS.