If you are using Maya, you may find the below resources helpful!
Links for HTML/CSS
Dropdown Menu: https://catalin.red/css3-dropdown-menu/
Not only do you want to know how users actually use the website, but you will also want to know if your code meets standards.
Here are a few validators to get you started with testing a website:
Google's Mobile-Friendly Test: https://www.google.com/webmasters/tools/mobile-friendly/
W3C mobileOK Checker: https://validator.w3.org/mobile/
W3C Markup Validation Service https://validator.w3.org/
WAVE: Web Accessibility Evaluation Tool: http://wave.webaim.org/
W3C Link Checker: https://validator.w3.org/checklink
CSS ONLY Navigation Bar:
The importance of Responsive Design
Responsive Design vs Adaptive Design Vs Fluid Design
Understanding Progressive Enhancement:
What’s the Difference Between Fixed, Fluid, Adaptive, and Responsive Web Design?