REST Countries API with color theme switcher

I have an issue that make the display glitch once opened on Iphone only but not in my computer browser (even in responsive mode), neither on android phone by the way.. i have no clue where the problem come from !

Despite this issue the site is running great, first time using JSON in JS to display element in HTML, had fun adding classes to change the theme of the site, i'm quit satisfied of the result.. i'm still looking to fix this Iphone glitch, if anyone have a clue where it can come from, let me know !