landing page with responsive css

Hi team, any feedback at all would be greatly appreciated.

There were two things i struggled with. 1: About 2/3 down the page the background changes colour. I was unsure how to do this. I tried looking for a solution but couldn't find one.

2: Secondly is how is set up my buttons. I made the <a> tag a block element in css and applied the same dimensions to it that i found in the Figma file. I'm not sure if this is industry practice. The way i used to do it was using padding on the <a> tag to reach the same dimension but i tried something different this time around.

cheers :))