Hey David, well done on this challenge 👏 It looks pretty close to the design, is responsive, the theme switcher works, and you included hover states on the cards. Your CSS is also organized nicely. I just have a few suggestions for you:
It would be nice if the switcher worked if the user clicked on any part of it, not just the circle part of it.
The design shows a hover state in light mode for when the user hovers over the switcher. The pill-shaped part of it should turn to the linear-gradient.
The layout starts to get a little wonky between 1000px and 1200px screen width because the large cards aren't centered with the small cards.
It would look nice if at tablet screen widths you had the cards laid out in two columns instead of jumping from four columns to one column at 1000px.