P5.js web editor vs gitpages - same code, different behavior

Using the p5 web editor I made a web app to run on the browser of a smart phone. I think made a git repo and copied all the code to the repo and hosted it on gitpages. The html, css, and sketch.js are the same, but when I go to the git-pages site on my phone, the resolution is much smaller than when I go to the site hosted by p5 web editor.
git-pages version
p5 web editor version
(The app only runs on mobile, so once you open the link, have the browser make a QR to share it with the phone.)
It feels similar to issues I’ve faced using the canvas html element and handling device-pixel ratios, but here it’s the same device each time and same code, so I’m at a loss.

In the index.html file changing the meta tag from

 <meta name="viewport" content="width=device-width, initial-scale=1">


  <meta name="viewport" content="width=320px, initial-scale=1">

seemed to work, but I would still appreciate insights about why this wasn’t necessary for p5 web editor.