In some mobile browsers that may be oldish but are still widely used, forum topics are displayed like shown in the example screenshot, which makes the forum unusable from there.
Screenshot: https://www.dropbox.com/s/n4nkxfajijm8u82/Screenshot_2018-01-26-16-57-05.png?dl=0
This specific picture is from Android 4.4.2 but I get the same result on Safari on iOS 7.1.