Letters are invisible in search box widget

I am using the Scribe theme (Upfront) and would like to use the Search widget in the header. The problem is that the search box is white and the font is defaulting to white. I'm assuming that the fix needs to be done in "CSS Styles and Anchor Settings". Please be specific with the coding. I have no clue, nor can I afford to mess things up by trial and error as my site is live. You can see the issue at https://faroutfab.com and try typing into the search bar.