Claude also helped me a lot and so did Github Copilot: CSS Variables — I set up –primary and other custom variables at the top of the file so I can change one color in one place and have it update everywhere. No more hunting through 50 random lines.100vh — For the activation screen, I used min-height: 100vh so it always fills the full screen height. vh just means “viewport height,” so 100vh = the whole screen.em and rem — When I used em, it scales based on the parent’s font size (like 1em = same size, 1.5em = 1.5× bigger). rem is more predictable because it always uses the root font size instead of the parent.inline-block — I used inline-block for elements that needed to sit next to each other but still have proper width and height. It’s basically the middle ground between inline and block.Flexbox — I used flexbox to lay things out cleanly in rows or columns, like the stat cards and the nav tabs. Way easier than messing with floats.CSS classes for show/hide — Instead of writing display: none in JavaScript everywhere, I just toggled a .hidden class. CSS handles the hiding, JS just switches the class.Activation screen background color — I can change the activation screen’s background by setting background-color on #activation-screen or .overlay in the CSS. I can make it any color or even a gradient. THERE was a lot of errors when I was typing but that was fixed. A big thing is that I also used OneCompilor tool which helped me compile my code and test it before showing it to claude which approved or disapproved it and then I carried on from there.