Improve print view styling

[tecosaur]

Here are a few small tweaks that I think improve the print style.

• Remove (useless) symbol definition underlines. These could be linked in the PDF (as in HTML), but they aren't, and so they end up being visual noise.
• Re-add the left cell border, in case the browser is hiding background colors, otherwise cells can look a bit funky.
• Hide the gutter element, it serves no purpose here.
• Hide the automatic page/url/date annotations

Before (Firefox default print settings)

After (Firefox default print settings)

[github-actions]

Try this Pull Request!

Open Julia and type:

julia> import Pkg
julia> Pkg.activate(temp=true)
julia> Pkg.add(url="https://github.com/tecosaur/Pluto.jl", rev="improve-print-view")
julia> using Pluto

[Pangoraw]

These could be linked in the PDF (as in HTML), but they aren't

I made an export (Chrome), and the global definitions actually have links targeting the defining cell. IMO it make sense to keep line numbers rather than hide them but it would be better if they were not selectable to enable easier copying from the pdf export.

[fonsp]

I want to keep the underlines because of #2450 and the gutters because of 33cb224 . Good point about making them not selectable!

[fonsp]

I removed the @page rules because we probably just want the user/browser to choose these settings.

It would be nice to set the "header/footer text" setting to false by default, but margin is not the right API to do that with, right? It looks like this is a trick to make the content flow on top of the headers, not an API to change the setting directly.

[tecosaur]

I removed the @page rules because we probably just want the user/browser to choose these settings.

Eh, I'm not sure about that, and it included size: auto; which should result in pretty sensible behaviour.

It looks like this is a trick to make the content flow on top of the headers, not an API to change the setting directly.

In a way it is, but you could then describe it as "a trick without side effects". The reality is, it seems to be the only way you can do so currently, and so I'd think worthwhile.