restrict zoom levels to 2 steps
restrict zoom levels to 2 steps

patrys/classjs-plugins,divio/classjs-plugins,divio/classjs-plugins,alesdotio/classjs-plugins,alesdotio/classjs-plugins,FinalAngel/classjs-plugins,patrys/classjs-plugins,alesdotio/classjs-plugins,patrys/classjs-plugins,FinalAngel/classjs-plugins