Popular content types like the accordion, grid, video embed, and media gallery aren't available for HTML Email, due to the comparatively primitive support for CSS and Javascript in web email clients.

This definition explains the meaning of CSS (cascading style sheets) and how using them with HTML pages is a user interface (UI) development best practice that complies with the separation of concerns ...

HTML has no equivalent features. HTML can't program a computer. Therefore, HTML is not a computer programming language. All modern webpages use a combination of CSS and HTML for layout and design ...