Fix vertical CSS alignment

I have some icons that need to stay perfectly aligned/centered vertically regardless of browser or resolution. It has MOSTLY worked except for firefox which is giving trouble. So the task is to assist me over teamviewer to resolve the issues. It would be a plus if you had both a mac and pc to see IE and safari firefox on your end. Everything must show the same regardless of the number of icons. Current attempt is using flexbox but firefox doesn't want to behave even with attempted browser-specific hacks. Summary: 1. Ensure buttons are vertically centered ideally using flexbox 2. Ensure both single or potentally unlimited numbers of buttons stay centered 3. Ensure it works in ALL possible browsers to test in. 4. Ensure it works in ALL possible resolutions.. I will re-iterate that you only get to work over teamviewer to my PC (on linux) to gain access to the files in phpstorm. I have gotten a majority of this task done, but this is going out of my experience. Lastly, use code word "css 2015" to prove your not a bot. Bids without this or mass spam posts by agencys WILL be ignored. I just need a skilled web designer to fix this so I can move on. Thank You.