Klatmon, I'm the author and lead maintainer of react-toolbox.com. I want to put you a bit more in context to understand what's going on.
The library is originally, and still, built with SASS. We've migrated already to PostCSS (there is a beta published) to fix issues regarding customization and building. I'm releasing a new package in a couple of days so you will see the reasoning behind this migration.
Cutomization is a problem really difficult to solve and it needs dedication. I'm putting a lot of effort on it but I can't review issues, solve doubts, fix bugs, work on new components, maintain the docs site, release new versions, keep dependencies updated, writing changelogs... and at the same time figuring out how to solve major problems like customization and workflow.
I'm one person without any funding or retribution. I have no help apart from sporadic contributions and some people helping with issues from time to time. I also have a full time job that keeps me away from dedicating as much time as I wanted.
Instead of being critical (and to hate being critical), you can contribute to the project. There is no need to write code or to fix bugs to contribute. It's enough responding issues, solving doubts... But please, don't be unfair. Open Source is built by everyone. If you see weaknesses, just try to help fix them, not just pointing at them. :)
About the changelog... there are no breaking changes, no major releases. You can see what's changing just by checking out the git history. I get is easier to check a note with the highlights but I need to assign priorities to move on. In any case I want to let you know that I plan to release a roadmap, along with an article and a new package during the next week.
I´m sorry the responsive version is not ready yet. The layout in the documentation is quite tricky and I haven't time yet to build media queries so you can use it on your phone.
Consider also that using the playground in a touch platform doesn't make too much sense, but sure I will make it responsive.