It needs to be clear when a legend is just a legend, vs. when it adjusts a chart.
Legends should all be the same text size/color
Legends should be written in Title Case
Dynamic legends that update the chart include a bit more fanciness:
A button style that outlines the active legend
A focus/hover style that highlights the...focused or hovered legend.
It needs to be clear when a legend is just a legend, vs. when it adjusts a chart.
Static Legends
Dynamic Legends