Adds a new offset marker on self at the position specified by value.
When the bar value is in the interval topped by value (or between value
and max-value in case the offset is the last one on the bar)
a style class named level-name will be applied
when rendering the level bar fill.
If another offset marker named name exists, its value will be
replaced by value.
Adds a new offset marker on self at the position specified by value. When the bar value is in the interval topped by value (or between value and max-value in case the offset is the last one on the bar) a style class named level-name will be applied when rendering the level bar fill. If another offset marker named name exists, its value will be replaced by value.