So many of us web developers and designers depend on WordPress to fulfil the needs of our customers, and it is often hard to find information on niche WP topics, especially things like making WP sites responsive. I know there are responsive themes available for WP, but that is only a small part of creating mobile-friendly sites.
So I opened Rachel's book with anticipation, having read some of her work before on various web sites, and I wasn't disappointed. She covers pretty much anything you could possibly need to get started in this area in a friendly approachable style, starting from the basics and moving up to more complicated topics. She starts off by giving sound advice on using mobile plugins and themes - great, because there is such a lot to choose from out there. The next major section of the book looks at using media queries to optimise different facets of your layout, from general containers, to nav menus, to text.
Then we get to the real meat of the responsive umbrella - responsive images. Rachel presents some pretty nifty techniques for making video and images responsive on a WP site, including serving different file size images, rather than just changing the display size.
The rest of the book concludes nicely, with tips for creative web app interfaces for WP sites, dynamically altering the content sent to (or displayed on) different devices using server- and client-side technologies, and how to handle testing and updates. If you're a WP developer working in this day and age, you'll probably find a lot of useful stuff crammed inside these pages.