Delayed style loading in a variety of browsers

[fosskers]

Everything works fine on desktop Chrome, as well as the built-in Gnome browser. However, things are strange on desktop Firefox, Tablet/Phone Chrome, and Safari+Chrome on iPhone.

Upon page load, before the user has interacted with anything, we see this weirdness (no centering has occured, giant quarter circle in the Button, footer is lifted up from its base position):

After an interaction has been performed (say clicking Submit without filling things out, to cause a Notification to occur):

Any thoughts?

[fosskers]

Another discovery: removing the NotificationCenter makes the button completely unclickable, so nothing can "jigger" the page to make the styles load if I do that.