Wordpress title won't change size

Between the posts and pages on my website, the h1 size won't change:

-https://harrysnell.com/how-to-supercharge-your-motivation/

-https://harrysnell.com/emotional-eating-course/

I've added to the CSS - h1.entry-title {font-size: 100px;}

In the first link (post) it changes, but in the second (a page) it doesn't. It seems to be overridden somewhere and I can't work out where.

Any ideas what's going on?