Power BI's visualizations have colors assigned automatically. It should be possible to set a color when a value is reached (e.g. always show negative bars in red) or for a particular color in a legen...
I've created a new idea (here: https://ideas.powerbi.com/forums/265200-power-bi-ideas/suggestions/12432660-dynamic-conditional-formatting-in-visuals-based-on) containing dynamic conditional formatting based on data (and not hard coded manual input). So people who agree that the above solution is not complete please help by voting!
