From what I can see, the input box z-index value is not calculated properly. Changing the width of the input field is not going to help, as it’s a flex layout element, and the browser will override it’s width automatically.
The simplest solution in my opinion is to use this custom CSS to reset the input box z-index:
[html]
.proinput {
z-index: 0 !important;
}[/html]