This is a Leaflet interactive choropleth map of Arizona's 30 legislative districts. In varying shades of red and blue, the map shows which political party holds the voter registration advantage, and the size of that advantage, in each district according to voter registration data published by the Arizona Secretary of State.
On hover, the map displays voter registration statistics for the hovered district, along with some other information. (On mobile devices, where hovering isn't a thing, the map will instead do this on a click.)