Sorry for the delayed response!
Try setting your header to
position:fixed instead, that way your image will scroll with the page as well. When I changed it to that you passed all the tests.
To fix your pricing/product boxes, you need to add
display: flex to your “buy” ID, and set it to
flex-flow: column in the mobile media query. (650px i assume you have it set as?)
And adjust the width of your header element to 100%… That should get your code working, more or less.
Moving forward, I suggest you practice on keeping your code a bit more organized. that way, it will be easier to figure out what you need to adjust, fix, add, etc… without having to refer to where things are in the HTML all the time. Though I know you mentioned you copied from the example, it’s still a good thing to keep in mind.
And as for the design, it’s actually easier (and more educational) for the most part to design on even just paper first, before jumping into code… that way you can lay out the code/page in a more organized way. But I digress, it’s of course your page - code/design it however you like. ^^