Web Design Stretching content to full width

Hello, I'm using this template:

Preview: https://freewebsitetemplates.com/preview/architecture
Download: https://freewebsitetemplates.com/download.php?template=architecture
Its CSS file: https://freewebsitetemplates.com/preview/architecture/style.css
Its main page: https://freewebsitetemplates.com/preview/architecture/index.html

I want to stretch its content horizontally, so that there won't be any free space on both right and left sides. I tried to edit CSS file and HTML source code to end up without any success.

Please help me or give me some idea.

 

Are you looking for something like this?

 

No, not exactly.

I want to stretch the entire content. Not the main inner section only.

 

Please take a look again. As you can see, the background images have to be stretched along with changing content width. I don't not know how to do that, maybe someone else here might.

 

you could resize the background images to the same value as the text, if I had to do this I would do it with the size in a percentage value, rather than a px or em value