Border on the Menu button

hi to you all

i have a problem with my site. the mobile version is showing a blue border on the menue button after clicking on it. see down below thos 2 blue lines. i have no glue how to remove this.

any idea?

• This topic was modified 6 years ago by amedeflum.
• This topic was modified 6 years ago by amedeflum.
• This topic was modified 6 years ago by amedeflum.

The page I need help with: [log in to see the link]