t/index.html: Make navigation menu options visible on load

The current VidGrind nav menu requires a click to expand to see the nav links.

I propose we have the nav menu display in entirety by default on desktop, removing the option to expand and hide the menu options. This will be good for when the site menu is integrated into the nav menu. The site menu should always be visible on page load to give context to the user about the information that they are seeing.