Supreme search category drop down width

Hi there.

Just wondering if anyone can help with setting a width for the advanced search category drop down?

On my site i am just wanting to use the category search drop down and the ‘near me’ button(i.e no ‘search for’ button)

On a desktop or tablet, these two float left and right respectively so looks fine, but when viewing on a mobile they dont ‘stack’ well on top of each other and so are different widths etc- which looks less than ideal. (please see images attached)

So was wanting to do two things…set a max width for each and to centre these on mobile view ? Is that possible?

Thanks in advance.

Ian