Fix a whole bunch of styling bugs

[ButteredCats]

In no particular order this fixes:

• Subreddit info overflowing on very small screens
• Posts having an odd right side gap shortly before swapping to the mobile layout
• The searchbox having a small gap on the right at and below 800px
• The sort submit button on user profile being too short at and below 480px (new bug introduced in 410872d)
• The search bar becoming scrollable slightly before swapping to the new mobile layout (new bug introduced in 410872d)
• Fixed and unfixed navbar options having differently spaces gaps between the content and the navbar
• Up/downvote numbers overflowing their container when in the extra small mobile layout
• 🐛 Bug Report: instance info page becomes unreadable if a field is too long #172
• Search box being slightly skewed offcenter
• Post flair not lining up with title text
• Post flair position being inconsistent between feed and inside of post (in the feed it was before the title, in the post it was after, now it appears in front in both)
• Slight vertical misalignments with text in the footer
• The footer text being off center in mobile mode
• The feeds button not appearing on the settings page, changing the size of the header
• Extra navbar padding on search page

It also removes an unused option for the mobile layout below 480px.

I plan on trying to tackle the odd gaps some pages have when the fixed navbar is enabled but it was becoming to chaotic to try and manage adding these on top of adding that. Added!

[ButteredCats]

Currently double checking everything and cleaning up any oddities I encounter, I'll leave another comment when all is good!

[ButteredCats]

Alright, I think that's all I've found that needed fixing. Tested it all in both Firefox and Google Chrome in desktop and mobile modes and all seems fine.

[sigaloid]

Thank you so much for this big PR! Never been good with CSS so fixing this was out of my depth but I've run into a number of these before.