Light and dark themes
Your board comes with both a light and a dark side, and your members choose which one they live in. Your job in Theme Studio is making sure both look intentional.
Editing each mode
Inside Theme Studio you switch between editing the light and the dark variant of your theme; the preview follows you, so you always see exactly what a member in that mode sees. Colors are set per mode, which is what makes a proper dark theme possible: not just inverted, but designed.
What members experience
The board header carries a mode toggle. Members flip it whenever they like, the board remembers their choice, and new visitors can follow their device's preference. You're not choosing for anyone; you're making both choices good.
Design your light mode first, then walk the dark variant right after while your choices are fresh. The classic dark-mode mistakes are pure black backgrounds (harsh) and forgetting the accent color needs more brightness on dark to keep its punch.
Checking your work
Before calling a theme done, flip the preview through both modes on the three pages that matter most: the board index, a topic, and a profile. If those three look right in both modes, the rest almost always follows.