Also on the mockup is a suggestion for UX on the settings UI, instead of a miriad of colorful icons for each section, maybe highlight only the pane that the user is currently on, and grey out the rest. A accented bar that matches the icon color also helps visualize this. And no need for text if we have the icons to express the metaphor. Also this way it becomes more color blind friendly, not sure if a color blind person would use a color picker too much, but usually it's good practice to consider this. The overall idea here is declutter. But please don't take this as criticism, there is nothing really wrong with your current design, it's just a suggestion really, a possibility.

And here, maybe an outline around the selected pane? To match the lines used elsewhere on the UI, rather than just a blank pane.

Improvments emitted by @cristianovitorino