Reverted filename container to its original CSS

Fixes filename container not lining up with editor, but has weird
padding-right attribute
Made filename container and editor pane line up

Made CSS changes so the filename container lines up correctly with
left-pane editor
Temporarily revert github button
Small change to not convert to markdown
TMP
tmp update
Fixed typo
Changed selector to 16px
Dropdown to choose what type of file gfm, markdown, html