The banner goes outside the width of the screen and the width changes by itself

Hi, today I found a bug concerning the css, in the mobile version both in the browser inspector and in a real mobile, the banner is out of the width of the screen, I leave photo.
I have also noticed that in the settings Appearance/Banner width in pixels, every time I switch between tabs in Appearance, the size is automatically modified and increases.

Thank you very much for sharing this wonderful plugin.