CSS File and style-custom.php File load long after rest of site

I have searched for days trying to figure this out. My URL is https://www.doityourselfrv.com. I have 2 files that are making my page load time jump and they are listed below. After using tools like gtmetrix and pingdom to analyze the issue these files below consistently cause the lag in page load. Though I am not what anyone consider a professional with this type of stuff I am eager to learn. I think the style-custom has something to do with the background image? If anyone has thoughts or could point me in the right direction of whats causing this that would be fantastic.

1. https://www.doityourselfrv.com/?mcsf_action=main_css&ver=3.5.1

2. https://www.doityourselfrv.com/wp-content/themes/bangkokpress/style-custom.php?