First you need to understand what they want to solve the problem. If you dont understand the question probably is because you are not reading carefully (or you need some rest) or you just have some lack of knowledge. It is normal tough.
So you could check for divs syntax, for example :
and see if that helps you understand the problem and thus solve it.
I hope that helps. Happy coding and dont give up!!
I’m not 100% sure but I think the problem is with how you have introduced your divs.
You have introduced 3 divs and then put each one after the other. Then you put all of their closing tags at the end. With this method, all of your divs will render on top of each other and it will look as if there’s only 1 div.
You should put each closing tag after its opening tag, like this:
This will make one bar with a height of 3 divs. If you want to see them as 3 separate bars you should put some top and bottom margins in CSS for your .marker class to see the difference.