How do I increase the font size for menu items on mobile Navigation, and change the menu burger from 2 lines to 3

Site URL: https://www.aphotois1000words.com

Hi,
Could you tell me how to:
- increase the font size for menu items on mobile Navigation  (i.e. "ice-teroids, winter wonderland, abstract", etc. see attached image) 
- ...and how to change the menu icon from a 2-line burger to a 3-line burger?  

Thank you so much!

Q1. Use this CSS

/* mobile items size */
#mobileNav a {
    font-size: 30px !important;
}

Q2. Which template do you use?