Make docs.rs UI left-aligned instead of centered

[jsha]

rustdoc's UI is left-aligned, including rustdoc displayed within docs.rs:

But if you visit a non-rustdoc page in docs.rs, for instance the crate page, the UI is centered:

In general I favor a centered UI, but I think for our use case the more important principle is consistency, so we should make the non-rustdoc pages left-aligned.

[syphar]

I'm with you here on consistency, though I don't know the reasoning for the current design of these pages.

[x1b6e6]

I think both pages should be centered. Look at these pages on a wide screen:

screenshots

The head should look forward and not to the left to avoid neck pain.

GitHub and other sites use content centered:

github, wikipedia and stackoverflow