customize availiability search box

site url: https://holidaynerium.com/

hello!

could someone help me apply custom CSS to the holiday apartment availability search box on my main page?

i would like to have the words 'ARRIVAL', 'DEPARTURE' and 'PERSONS' to be white and not gray.

alternatively, if it's possible for the entire box surrounding the search bar to have a white background with some transparency? i'd like to try both and see what looks better. (something that looks like the image below, just the white background with its opacity changed)

thank you! i'll try fiddling with it there