Happy to answer any questions about it!
Question, though: if this book is specifically geared towards web apps, why did you give it such an ambiguous name that mentions nothing at all about web apps?
Is your book about architecting applications (on a code level), or is the "design" relating more to the artistic definition of design? Judging by the sample content, it looks to have little-to-nothing to do with actual code, and mostly focused on UI/UX.
As-is, the title just seems really inaccurate; "software design", at least for me, is a very specific area which deals exclusively with UML and other code-level architectural concerns.
The book is focused on designing software from a user's perspective. That includes how the application flow works, making sure it is intuitive, and adding a layer of polish with colors, textures, and animations.
Looks to be an excellent and interesting book though, I'm just doing the Human Computer Interaction course on coursera and I can see it being a nice addition to fleshing out some of the topics.
I would love better ideas!
"The Web Design Handbook"
"Web Designs Handbook"
"The Handbook of Web Design"
Also, you might be able to get away with just giving it a subtitle, which would add context. Maybe include UI, UX, graphic design, usability, etc.
So mentioning applications or software is important.