How do I center my webpage content on large screens? There's a white space on right side.

Site URL: http://www.mollyrees.com

Hi!

I've had this problem for a few years and would finally like to fix it. There's a large white space on the right-hand side of my screen when I open my website on a wide screen. I'd like the webpage to be centered, with equal padding on each side. I added a custom border a long time ago, and I'm sure I added some custom CSS that messed it up. I'm looking for some way to fix it without deleting all the code (which I still need for other parts of the website.)  I've attached a screenshot so you can see what I mean. Thanks to anyone who can help!

Add to Design > Custom CSS

div#canvas {
    margin: 0 auto;
}

@tuanphanwow! Thank you so much! This totally worked. I added   margin-top: 15px !important;  so that there was a little space above the line border. It would be nice if there were a little space around that line border as well when the screen is smaller, but I think it's not a big deal. Thank you thank you! This is something I've been trying to fix for literally years.

This is a bit off topic but your site is really good elegant site. Avenue is a very versatile 7.0 template regardless of its age. I use it it too. I will be reading your "writing" on a regular basis. I also admire your photographs. I would appreciate your opinion of my photo lessons that I have posted on my site, if you wish to read them.  They are are a mixture of choosing equipment and shooting advice. 

my random views

Derrick. 

@derricksrandomviews, I just wanted to say thank you for your comment and for looking at my site. I read a lot of yours as well, and was very moved by the personal writing about your families story. It actually inspired me to begin work on a personal photography project about "miracles" that I've been thinking about for a long time. I'm very happy that you shared your site with me.

Your very welcome, and I look forward to seeing your photo project. And thank you too.