Chrome iOS Pseudo-Class Sibling Selector Bug
input[type="radio"]:checked ~ label.radio
I’ll cut right to the fix, and then give some more background the on bug.
input[type="radio"]:checked + label.radio
It appears that this bug has some history. CSS Tricks had a good article about this bug back in 2011 with plenty of sources. In the CSS Tricks Almanac entry for the general sibling selector, there’s a comment from November 19th, 2015, that a recent Chrome build for iOS9 reintroduced the bug.
Hopefully the Chrome iOS Team will get a fix out for this bug, soon! I’ll update this post when that happens.