Having a problem with a website on iPhone

Hi,

I'm fairly new to web development and I'm currently just playing around making websites to practice. I've uploaded one to github and sent it over to a friend to check how it looks on iPhone and apparantly one of the sections has completely collapsed and the landing page isn't displaying properly.

Problem is I have a Galaxy S7 and not an iPhone so I can't check if it's an issue across all iPhones, if someone could test it on their phone that would be awesome. And even better if someone knows how to solve the problem. The website is https://martellis.github.io/penguins/.

Here's some pictures of how the landing page and section SHOULD look and how they are apparantly appearing on an iPhone. https://imgur.com/a/02Nbl

Any help is massively appreciated :)

EDIT: Here's a link to the code https://github.com/MartEllis/penguins?files=1