Search bar changes

My quuery is regarding the search bar (on all pages of website)
I would like to remove the option of “what to search for” and only have the option for users to search by location.

I found this code from another query to address this:

.search_text {
display: none !important;
}

This code works and removes the “what to search for” part of the search bar, however it leaves the location search bar on the right hand side. Please explain how I can centre the search bar once the “what to search for” has been removed.

Furthermore the entire search bar section appears to have a light grey background, how can I change this so it is white.

website url is: http://www.findcrossfit.com.au