FAQ-accordion (HTML and CSS only)

Hello! I just finished learning the basics of HTML and CSS so I wanted to get some practice in. This is my first-ever challenge on GitHub! Unfortunately, I haven't learned Java Script yet so I couldn't make this website interactive, so here's the design part! I've had some trouble trying to fit the background pattern into the top part of the page, which is why my CSS code for it is messy. I made the width of the image 100% so that it covers the entire width of the page, at the same time trying to make the height smaller. But doing so made the width of the image smaller even though it's still 100% and I don't understand why. Any feedback would be appreciated!