Recently I added a gallery to my website - I am usually not using galleries much. Initial problem was that the thumbnails were too small, so I increased the thumbnail size and recreated existing thumbnails with a plugin (there are several). At that time, when I started to build the theme I had the responsiveness removed for the side to be static.
In the meantime I changed my mind and re-enabled responsiveness, now leaving me with the problem that the thumbnails (that are inserted without an option I could change by selection - or am I missing something?) are obviously too small at certain screen sizes. To solve the problem the gallery images would need to have the img-responsive class applied and full-width images used instead of thumbnails.
What would be the best way to accomplish this with the greatest amount of compatibility (to existing standards)?