How do I properly configure the custom weather forecast card colors?

The two settings do diferent jobs. The card colour is the background of the card itself, and the active colour is what lights up when a card is in use or engaged, like a light card glowing when the light is on. Once you think of it that way it clicks. So if you pick a dark navy background for your cards, set the active colour to something bright enough to pop against that navy, not a colour you want as the base.

For the forecast readability, the trick is contrast between the text and whatever sits behind it. On my 7 inch panel I found light text on a dark card background reads way better than trying to darken the text on a light background, especially with the smaller forecast rows. The forecast details sit on top of the card background, so if your background colour is too close to the text colour it all mushes togehter. Pick a background that is clearly darker or clearly lighter than the text and you will be fine. I also stopped trying to use mid-tone colours entirely. Colours right in the middle of the brightness range are where contrast dies. One thing that helped was keeping the whole palette to two or three colours total. I use one background colour across every card, one accent, and let the active colour be the accent. Feels intentional instead of a rainbow of cards fighting each other. On the corner curves, it is genuinely personal preference. Small looks tighter and more technical, large looks softer and more friendly. I went medium on the 7 inch because at that size the large curve eats a bit of visible space at the card edges, and on a 7 inch you want every millimetre for content. On a smaller panel I would probly go small for the same reason. Whichever you pick, it applies consistently across all cards so the cohesion comes free.

Also worth a try, resizing the weather card bigger by dragging the corner. The layout adapts to card size, and giving the forecast more room solved half of my bleed-into-background issues on its own.

One thing that saved me a lot of trial and error was taking a screenshot of the dashboard and dropping it into a colour picker tool. Sounds overkill but seeing the actual hex values side by side made it obvious when my text and card colours were only a shade apart. On my wall panel the screen washes things out compared to my monitor, so what looked fine on the PC was muddy in person. I ended up nudging my text colour lighter til the picker showed a real gap, then pushed the same change back into the config. Also, matte screen covers change how saturated colours look, so test on the actual panel before settling on your palette.

I'm skeptical about the idea of keeping the whole palette restricted to only two or three colors total. Even though limiting colors seems like the easiest way to get cohesion, I think it can make the whole thing look extremely basic or clinical. I found that trying to fit everything into just two colors made the dashboard look dull, so I ended up using four or five distinct colors to separate different types of information instead. It took more work to balance the tones, but the end result felt much richer.

One thing I'd add about contrast is that a wall panel gets judged from across the room, not at arm's length, so I test every theme by standing where I'd actually glance at it, usally three or four metres back under the room's evening lighting. Text that seems crisp on the bench turns mushy at that distance, and a combination that survives the daylight-to-lamp-light swing is the one I keep. I also check it with the screen brightness at both ends of its range, becuase my panel sits near a window and the afternoon sun flattens anything but the starkest pairings.

I tried the dragging the corner thing on mine last night and the forecast did get easier to read, but now my other cards look tiny next to it and the whole screen feels lopsided. Is there a way to make them all snap back to matching sizes after you resize one? Also still fuzzy on wether the corner curve thing is a one time choice for everything or if each card can have its own. My wife wants the soft friendly look but I keep picking the tight boxy style, so it would be nice if we could each get our way on different cards.