HTML5: The Missing Manual, 2nd Edition

Chapter 7. Responsive Web Design with CSS3

When web designers first started putting their content into HTML pages, they faced a challenge. Whereas print designers could rely on certain assumptions about how their documents would be arranged on paper and how they would be read by their audiences, the online world was loose and lawless. Depending on the user’s browser (and personal preferences), the same HTML page might appear wedged in a tiny window or floating in a giant one. This made complex layouts risky. A layout that looked perfect in one window could easily turn into an awkward and ungainly mess when viewed in a window with different proportions.

Today, this variability has only increased. Not only do web designers need to think about different sizes of browser windows on desktop computers, but they also need to accommodate different sizes of devices, like tablets and smartphones. And at the same time, website layouts have become more intricate, with most sites now composed of menus, navigation aids, sidebars, and so on. If your goal is to create a single website that can shift gracefully between different viewing contexts, these details present a significant challenge.

Because web designers have long since outsourced the layout and formatting work of their web pages to CSS, it makes sense for CSS to provide the solution for this problem. Fortunately, CSS3 has the perfect tool: a feature called media queries, which lets your website seamlessly switch from one set of styles ...