Mobile Menu Bar Size

Hi guys, on harmonyhomeimprovements.co.uk the menu bar on mobiles - portrait view - is very deep. This is due principally to my customers name being so long, thus forcing the hamburger menu onto the next line, but I was wondering if you have recommendations to reduce the size please? Desktop and mobile landscape views are all fine. I can obviously reduce the letters in the site title, but is that the only option? Thanks, Chris