I tested on mobile as you suggested, and noticed an unwanted horizontal scrolling of about 20 pixels. I assume this is probably a bug to be fixed later.
I tried to replicate your and other commenters experience. I found issues on Android's default browser that didn't exist on my first, Chrome test. Did you use default browser or what browser you on?
My apologies, I didn't see your message on time. I used the default Chrome browser on my OnePlus One running CyanogenOS 13 (Android 6.0). I should have posted this in my first comment itself.
Interestingly, I did not see any horizontal scrolling when I tried in Chrome browser (Mac OSX 10.11.4) in regular user mode. But on toggling device mode (in dev tools), and selecting one of the mobiles - Galaxy S5 or Nexus 6P, the horizontal scrolling started to appear, and it is a lot worse than on my actual android phone.
I haven't yet been able to identify the element that overflows, but the <html> and <body> seems to take default 100% width and are expected to be contained within the browser frame. There is some other rogue element, somewhere nested inside, which is causing this unwanted horizontal scrolling.
I think the horizontal scrolling is happening only in that github.io web page, and probably not a fault with the CSS framework itself. The framework looks nice and small, and a good alternative to the mainstream alternatives.
You're welcome and that's relatively tiny. :) It's actually a variant of an old-school approach of developing on underpowered, older systems to maximize responsiveness. Apps, web sites, databases, whatever. I mean, there's features in modern CPU's that almost everyone has that you can optimize for. Do that for sure but make your baseline efficient even on lowest, common denominator.
Means it will run like a McLaren F1 on the modern stuff with almost no resource requirements. Ironically, it didn't matter all that much on desktops and servers. The new trends of mobile browsers and pay-per-CPU-or-whatever clouds mean it brings more benefit than ever. Especially at scale.
https://news.ycombinator.com/item?id=11764257
I tried to replicate your and other commenters experience. I found issues on Android's default browser that didn't exist on my first, Chrome test. Did you use default browser or what browser you on?