Monkey Raptor

I experienced this while using Firefox browser on Android.

My HTML had this in the head section:

That tag is to inform the mobile browser to "fit" the screen width (kind of normalization) with the page it's currently at, and with initial scaling of 1.0 (100%).

On mobile Chrome, that tag works. But on Firefox on Android, it breaks. Firefox on Android ignores the all-capitalized meta viewport tag.

Therefore, I switched it using all lowercase.

That solves it.