An example how to make a quiz with you-draw-it with displaying reference values. Reference values are styled individually. For the bar chart, the option question.referenceShape is set to “tick”.
For documentation see https://github.com/EE2dev/you-draw-it
Adopted the you-draw-it implementation from the great work at https://github.com/wdr-data/you-draw-it. Original idea developed by the New York Times.