Mobile menu not displaying correctly

Hi,

The site I am asking about is https://www.italiantravelconnection.co.uk and concerns use on mobile phones.

I manage a website for a small tour operator and on a pc the top menu works fine offering a drop down when hovering over the holidays tab, but on a mobile when clicking on the 3 lines it takes over the screen and does not scroll correctly to offer all of the options.

I checked other posts on this forum and noticed one that suggested adding the following CSS:

.smartlib-smaller-topbar{
height: 100%;
overflow: scroll;
}

I tried adding this and this helped to allow the menu to scroll but then created another issue by obscuring the homepage with the menu background colour most of the time with no way to get it back to normal.

I have since removed the CSS again but would appreciate any assistance. I do have the option of removing the drop down menu but would prefer not to however a lot of our referral traffic seems to be on mobile so this is affecting our ability to communicate our services correctly.

I have checked this on a number of mobile devices, mainly on chrome browsers.