Well, I don't have much information about design and style guidelines- and the web is crazy about Material Design guidelines. So, I was wondering if there are other style guidelines present as well. Let me know in the discussions.
Another one that was and kind of is: Flat Design. When Flat Design arrived was kind of weird because everyone were using texture and trying to make it feel like you were using real objects like paper but just being delivered in digital. I don't remember the name of the iOS design style but when it arrived it blow everyones minds... although it was already being used the Flat style but wasn't really approached until iOS 7 (if I recall it right).
Now the tendency is to use whatever you like but taking in mind performance, and requests... so Material and Flat Design is the best way to go to avoid using a lot of images on your Front-End and trying to do everything or most of it with just CSS.
I like the details they put in into Intuits Harmony style guide. The guide is comprised of web, ios and android styles. For instance you will find detailed explanation on designing navigation on each of the platform in its unique way.
http://harmony.intuit.com/
Blog post - developer.intuit.com/hub/blog/2015/01/08/new-year…
Denny Trebbin
Lead Fullstack Developer. Experimenting with bleeding-edge tech. Irregularly DJ. Hobby drone pilot. Amateur photographer.
Nearly each company has its style guide, but not all are public. IMO, Material by Google is famous because it is the simplest I can think of. Using shadows to highlight and separate is brilliant.