I decided to build CSS Scan to get computed styles with no hassle and in real-time. It's faster than using browsers' Developer Tools and give all of the styles in the shorthand way, this means no messy CSS or styles being overwritten. You can also copy to clipboard by just clicking on it.
P.S.: Of course this is only for use cases you want to have an overall vision of the styles; it's far from being a full alternative to Inspect Element.
It took me 50 hours and 17 minutes to develop. Inspired by @levelsio I recorded all the development and made a speed video. If you want to check it:
Glad you got off the sofa a few times during the code-a-thon, you could have spent all that time in front of a games console, so well done for completing the task.