Single File Mode: fix layout and make optional

[arturi]

• Significantly improved styling on different screen sizes
• New option centerSingleFile, true by default, but some might still like to disabled it, in my opinion this is too opinionated and new to force on all users.
• Fixed “ghosts” for Golden Retriever

Now:

Tall:

Shorter, truncated file name:

Too short for Single File mode, default to regular grid

Mobile:

Before:

todo:

• fix icons for file types on different screen sizes
• update docs on uppy.io

[Murderlon]

This is a lot better!

As a last improvement, can we get rid of the white box around a picture? It doesn't add any value I think. We can let filename wrap into another line if that's required in less wide cases.

[nqst]

Here is something I'd like to be fixed:

1. If a small image is uploaded, it's scaled up. We can only reduce width/height.
2. Transparency is not rendered properly, there's a black background instead.

3. Icon file previews look incorrect:

4. I think in lot of cases we could leave the white background out:

[nqst]

Can we get rid of the white box around a picture? It doesn't add any value I think. We can let filename wrap into another line if that's required in less wide cases.

I think in case of very small of very narrow images it adds value — there's a point where wrapping won't make sense. But in the current version the white box looks quite too contrast, and we can use it in less cases (see the last screenshot in the review above).

I propose to remove the box-shadow, and set the 50% opacity for the white background. It can look like this: