When doing responsive design you want to test the changes made on your iPhone the same way you test it in your browser, by browsing to localhost.
But how can I access the localhost on my Mac? It’s quite easy, you need to enter the name of your Mac in the URL.
For example in my case I need to enter http://Andreas-MacBook-Pro.local as the URL in Safari on my iPhone.
That’s it! No more need of uploading HTML files to remote web servers in order to test the HTML and CSS.
I’ve only tried this on iPhone and iPad but I guess it will work on Android devices as well.