How to compare two files in vim

`j` / `↓`	Next post (in feeds)
`k` / `↑`	Previous post (in feeds)
`Enter` / `o`	Open highlighted post
`Shift` `O`	Open in new tab
`g` `h`	Go to home
`g` `s`	Focus search
`[` / `Shift` `K`	Previous post in series (or previous page)
`]` / `Shift` `J`	Next post in series (or next page)
`b`	Toggle left sidebar
`Shift` `B`	Toggle right sidebar
`s`	Toggle reader mode (posts) / simple/rich view (feeds)