I've found several tutorials about how to create a new responsive Drupal theme, but nothing for how to make an existing theme responsive. Do you have any suggestions? Is it a matter of going in and making sure that I'm using em and percentages plus creating multiple stylesheets?
My second question is what responsive and grid framework do you recommend for a new site? We'll be moving to Drupal 8 next year and I want to get familiar with the best framework now!