With websites, desktop apps, etc., I've experienced over the years one thing :: trust your eyes! With certain operating systems, well, one in particular, I trust even less.

My main workstation has four monitors. When I'm doing anything "code" related I have a text editor (
Geany) open on the bottom-left screen to do things like copy/paste confirmation all the way down to highlighting an entire web page (source) and dumping it for search/replace which helps with stripping Windows Line Feeds (\r\n) and/or Linux' (\n) and reorganizing tab/spacing... little things that are big annoyances to me and make things easier for my eyes and brain to process.
It's just a matter of preference.

OH... there's also browser differences. For example, when I'm on the forum here in FireFox, the WYSIWYG editor when you reply or post something has some strange quirks. For example, if I type a line and press <ENTER> and then type a second line, they merge into one. To actually move down a line in the post itself, I have to <ENTER> twice. To create an empty line between, <ENTER>
three times. Bullets, code/quote, etc. take a little more finesse as I'm not much of a mouse person.