Wrong hamburger icon on 7.1

Hi. I've noticed that the hamburger icon on 7.1, which on my site comes up with a narrow window or on mobile, is strangely only 2 lines rather than the standard 3. I've had feedback from a friend saying that it might not be immediately clear on mobile that the 2 thin lines lead to a menu, whereas a bolder one with the usual 3 would be more obvious. The helpdesk told me there's no way around this apart from with custom code so can somebody please help me with how to achieve this? 

Can you provide a link to your website? Please send the password if it is pwd protected.

Hi sorry for the late response. It’s www.LPIclinic.com

I found the solution here 

but I had to change the link to a three line menu icon not a literal hamburger (!)