Mobile site now has border

Hi, Love the site! I've just noticed an issue that I will need your help with. My website (ourladyofsorrowsschool.org) has a grey border when viewed on desktop computers, but no border when viewed on mobile phones. This is how I want the site to appear on mobile phones. However, I noticed that the grey border is now appearing on mobile phones as well. Can you help me hide this border from the mobile phone experience? Thank you. FM