I need a single web page changed modifying position on screen.

On all pages of my web site the main content is currently off-center on screen and the background outside the content container is filled with a repeating background image.

I want one index.php file and its header.php (and possibly footer.php if necessary) to make changes.
On quick review, only the header.php file may require adjustment.

1. Center the main content container on screen.
2. Widen the content container to 1014px without widening or changing the position any of the content within this container.
3. Add a left and right shadow outside the left and right edge of the 1014 content that matches the current drop shadow on this page. The shadow can be done as an image background if necessary since it is equal left and right.
4. Code changes should be discreet and minimal as needed, not any type of whole page conversion.

An authenticated drag and drop ftp link will be provided to development a folder that contains this page and all supporting files to display it in-full from your browser. This link works from windows, Just click the shortcut on your desktop or drag a file to the shortcut on your desktop. You don't need to copy everything to your development platform because drag and drop file access provides instant verification of your changes with your browser.

This is the live page that we want changed. All required files will be will be copied to a development folder.
https://mygig-disk.com/index.php

Please note the white background surrounding the content is wider on the revised page. 1014px wide.
** Probably should center the existing container in a new wider container so margins controlling width and position of existing content does not have to be adjusted.

I will do the other 40 pages of this site, based on the changes you make to index.php. I could no this myself but I would be very slow and I have other deadlines to meet.

This page is built with a few includes - only the header.php and footer.php include may need modification. The goal is to spread this new configuration to 40 other pages, so don't restructure the used of includes.

See attached image for a mock-up of the revised page.