I’ve edited your post for readability. When you enter a code block into the forum, remember to precede it with a line of three backticks and follow it with a line of three backticks to make easier to read. See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.
I’m not sure what you’re after, but you’ve misspelled class in your <ul> element. Try fixing that. If you’re still having problems, could you post your code in an online editor like Codepen?
It also looks like your opening nav tag is actually a closing one. Just remove the dash, and fix the class typo in your ul tag. Let us know how it goes.
I am having the same problem with my ul, as the li items continued to be stacked instead of inline in the header. The last suggestion of adding the class=“navbar-expand-md” worked in Codepen, but now the li items are all clustered together as if to be one long item. Here Is my code. I am using Codepen and IE 11 which I believe supports Bootstrap just fine. I tried it in Chrome and Edge with the same result. I also referenced the material on nav from the FCC guides and searched. I made sure bootstrap 4 was added. Now I am asking.