CSS or pages.php Problem?

I am rather new to custom coding and have a problem with the main content area of my site (building it locally). Everything seems placed where it should be on my home.php (static), but there is a large gap between the header and the actual content when the site access the page.php.

Any help for eliminating the gap between the header and the pages content would be very appreciated.

My style.css is at https://wordpress.pastebin.ca/2078342.

The code for home.php and page.php is at https://wordpress.pastebin.ca/2078345.