Why are html select tags not opening when viewing website in fullscreen?

So I created a this landing page for a website that uses HTML, CSS, JavaScript and Bootstrap. I noticed a weird bug which I am unable to pinpoint. When I click on the loanAmount or loanTerm <select> tags (inside "Loan Details" container) they do not expand to display <option> tags. However, that issue is only there when I view the website in fullscreen (maximized). The <select> tag becomes clickable again when I reduce the browser's window size to anything other than fullscreen. I have also noticed that the <select> starts working again when I open the Chrome's dev tools, even though I am viewing the website in fullscreen. The dev console does not produce any errors when I click on <select> so I have zero clue of what could be the issues. Could anyone please take a look at it and tell me where this bug is stemming from? I have a feeling it has something to do with media queries but I am unable to identify the exact problem.

Hosted website: https://affectionate-kepler-e00a08.netlify.com/

Code: https://github.com/rimeikis/loan-company-front-page