Check out a free preview of the full Responsive HTML Email Design course:
The "Using Media Queries" Lesson is part of the full, Responsive HTML Email Design course featured in this preview video. Here's what you'd learn in this lesson:
Media queries are sets of conditional statements added to CSS to change the layout/style of a document. They are not supported in every email client, though. Justine explains how to use media queries and the caveats they bring.