OP. your code is also not correct. You have more than one element named with the same id. Id's must be unique and cannot be reused. Classes, however can be duplicated as needed.
Also, why not use an unordered list for those nav links? Thats basically what a nav menu is, a list of buttons, links, items, etc. Much more semantic that way.
I literally just started learning Html /CSS / Java a month ago; spare no details!