Surprise Bootstrap?

Let me start by saying that I am attempting to learn Bootstrap, and am still not sure exactly what I am doing. So please try to be understanding if you want to help.

I've made some now-outdated html websites in the past, and have a little understanding of what Bootstrap is. So I've been messing around with the templates, and also trying to learn how to convert an html site to Bootstrap. Anyway, without doing anything (as far as I know)  to my old portfolio website, the top navigation on ONE of my eleven pages mysteriously is more viewable on my phone, as if something changed to make it more Bootstrappy.  I thought there was a lot more involved with updating the html, and other code, and for this to happen without me doing anything is confusing.

Would an expert be able to look at code on these two pages, and tell my why the navigation on misc.html views better on a mobile device than advertising.html?

This one looks readable on my phone:
http://www.christinespidell.com/portfolio/misc.html

This one (plus all of the other pages) looks smaller, and like regular html.
http://www.christinespidell.com/portfolio/advertising.html

I can't find any differences in the actual code, so it's really hard to figure out what changed in the misc.html code.

If it seems like I'm in way over my head, I am. I just want to figure out why one page changed on its own. Then I'll dive into Bootstrap tutorials. Is anyone willing to look at the code on these two pages to see anything obviously different?

Thank you!