Air3 is a responsive FluxBB skin based on Air and Victory which looks great on all screen sizes - from widescreen desktops to tablets and smartphones. It is kept as close as possible to the default Air.
There are also scripts available but they belong to the creator of Victory and they will be removed later.
Download from https://github.com/natrius/air3/releases/latest and unzip the package into the styles/ directory of your FluxBB installation. The styles/ folder should now contain air3.css and air3/. After this is done you can select Air3 in your profile.
Created for 1.5, may work on older versions as well.