Hey, good work on this one. The layout in desktop is good and the mobile state as well. Though there are couple of suggestions
Font. I think you are rendering the wrong font in here, since the original uses a sans-serif type and you are using a serif type.
Horizontal scrollbar. When resizing, a horizontal scrollbar appears at the bottom which we do not want. It was caused by the declaration of
width: 80.5%in your
header sectionselector. Try to remove that and it will remove the scrollbar. Though when you use that, you need to adjust as well the sizing of the image inside it.
Regarding your query. Well the left pattern will not stay in place, because the container which is currently contained, have a scaling sizes. Meaning the container will resize so is the left background pattern. But if you made the container have a fixed size, then the pattern will stay in place.
If you need help, just ask here okay and you work is good as well^