Flatiron Template - add groups of galleries inside index page?

Hello. Here's my website. I'm using the Flatiron template. My landing page and main place for content is an index page, with each page within being a gallery with text and maybe a video or image or two. I'm a big fan of how this looks and works.

BUT I'm trying to see if I can do something. I want to have the "work" link at the banner actually be a drop-down menu, in addition to my landing page (which I don't want to change). I'd love to create a similar effect to the main "work" index but specific certain types of work within, i.e. narrative, commercial, music video, etc. That way the viewer can link directly to certain types of projects, and see it in the same type of view. HOWEVER, I don't want my main work landing page to change at all.

Would this be possible with CSS code? Is there a different template? Please help! I don't know how to code but I'm eager to solve this.