XHTML is a variant of HTML that uses the syntax of XML, the Extensible Markup Language. XHTML has all the same elements (for paragraphs, etc.) as the HTML variant, but the syntax is slightly different. Because XHTML is an XML application, you can use other XML tools with it (such as XSLT, a language for transforming XML content).
CSS handles the look and feel phase of a website page. With CSS in use, designer can handle the color of the text, the spacing between the paragraphs, the font style of the text, the way columns are shown and organized, what images or colors are retrieved, layout formats, and responsiveness of website for separate devices and monitors. CSS is easy to learn as well as offers strong control over the management of HTML file. Most frequently, CSS is a joint collection with the markup languages like the HTML and its different versions.