Coding for Header / Navigation Menu Functionality Behavior

I'm working on a website design project and need the header & navigation menu looks and functionality to match a site that the client likes. Specifically here are the details: 1) You can view the header & navigation menu of what will be the home page at: [login to view URL] 2) The client wants the header & navigation menu to behave EXACTLY like the menu on this website: [login to view URL] -- this site has a transparent header that overlays over the videos and then a translucent background on the sticky header as you downt he page. Most important to the client is the behavior of the menu: a) the top level menu items need to be white by default and have have a horizontal line under them b) When you click on any of the top-level menu items, a full-width, translucent mega-menu area opens up and presents the sub-menu items in a vertical listing for each of the menu items c) When the mega-menu box opens up, all of the top-level and sub-menu items are black by default, but when you hover a top-level menu item, ALL of the menu items in that section change to a different color. (For example on the methodhome site, when you click on "What's New" top level menu item, the mega menu area opens and the text color of What's New and all of the sub-menu items in the section change to the hover color of purple) 3) The default font of the theme for the menu was "Roboto" and text transformation = UPPERCASE. I have already changed the default menu font style from Roboto to "Nunito 700" (which is very close to the font sytle of Avenir 65 that is use don the [login to view URL] website). I have set Nunito 700 for the top-level menu items and Nunito 600 for the sub-menu items. 4) I need the header / menu look and behavior to be constant against all pages. The theme being used on the site has a few different headers so I'm not sure if you can edit the code for an existing header to create a new one with the menu functionality behavior desired. I need this project worked on today so that I can get this task completed for the client and have them review for approval / completion. Thanks for your assistance in advance.