How to shorten blank of site-title Image on mobilephone or tablet

I’d like to ask how to shorten the blank of site-title image on mobile-phone (iPhone7) or Tablet.
Which part of CSS should I edit?
I attached screenshot.

Hey there,
I hope you’re doing well today

Please provide me with the URL to your website so I can investigate the issue for you.
Based on your screenshot it seems like you’ve made some customizations to your site,
that may or may not affect the possible CSS solution to be provided to you.

Best Regards,