It's amazing what lengths people go to in order to get custom colors and fonts: they'll decompile apks and upload new ones with a custom colors.xml; they'll roo

It's amazing what lengths people go to in order to get custom colors and fonts: they'll decompile apks and upload new ones with a custom colors.xml; they'll root their phone and change the colors in the OS; or they'll install a binary of unknown providence where someone else did this. There are things you can do to make it easier. You can provide settings for specific elements (for example, HN has "topcolor" in user settings). If you're doing a web app, keep the markup simple so that one can use per-domain user stylesheets (try inspecting the markup of a HN page). If you're doing a Windows app, use native controls so they can be themed by the OS. But these decisions constrain what product and graphics designers can do, so you need buy-in from the other parts of your team.