Meagan Longoria looks at contrast:
Since conditional formatting was released for Power BI, I have seen countless examples of bar charts that have a gradient color fill. If you aren’t careful about the gradient colors (maybe you just used the default colors), you will end up with poor color contrast. Luckily there are a couple of quick (less than 30 seconds for most people to implement) fixes that can improve your color contrast.
Click through for a video demonstration and two tips from Meagan.