Responsive width

I created a child for Aventurine theme and everything looked great – on my laptop and my iPhone. The site was displaying full screen width on my iPhone but then, something happened. I need to get the site to display full screen no matter what device. Here’s what I think happened:

While viewing the site in Chrome, I left clicked and chose inspect. I’m thinking I may have toggled to the device mode which shows the ruler at the top of the screen. I do remember playing with the ruler but then, I couldn’t get the blue ruler to move to the right any longer. This is when the site naplesdisabledveteransbanquet.org began showing up half-width on my iPhone.

Any idea what to do to make it set again at “full width”?

Thank you.