Fix Yoast XML and frontend banner

Hi, I developed a website using Wordpress and Yoast SEO Premium. I would like to solve the following issues: 1. Sometimes, my website’s banner is defected (cut off) on mobile devices, particularly iPhones. I will show you the screenshot in private chat. Right now it looks okay (at least on my device), but I dont know when it’s going to start to act up again. I’m not sure but I think minification causes this. 2. XML: My website’s XML is generated by Yoast Premium plugin. However, it produces an error when I visit my XML link. After I contacted Yoast, they said it’s not caused by their plugin, but rather by empty lines in my [login to view URL] file. That turned out to be correct. After i removed the empty lines in my [login to view URL] file of my child theme, error in my XML was fixed. However, my website’s banner at frontend was impaired again: it used to have defects occasionally, but after I fixed XML, the defect in banner became permanent. So now I have to keep the empty lines in my [login to view URL] file in order to make the banner look nice… Can someone help me counter this issue? I want to be able to remove error from my XML and keep my website to look nice. Thanks. IMPORTANT NOTES: 1. Please solve these problems without touching the parent theme. 2. I cannot give you my Wordpress or FTP login details. So I need you to show me instructions via texts or Teamviewer. Thanks.