Improve appearance of the slug field in the "Edit Post" page in the administration

[tyxla]

The slug field could use a couple of minor general improvements:

1. The input has always been lacking a proper CSS width. Since there is nothing else in the slug meta box, the input can be extended to 100% width. I have observed the narrow slug field in as soon as version 3.0.
2. The slug input horizontal/vertical centering within the meta box content div varies throughout the different versions. In 3.0, 4.1, and in trunk as well, there is more space at the bottom of the field, than at the top. Since the spacing on the sides is 12px, I suggest that the total top & bottom margin of the field within the slug box is also changed to 12px for consistency.

[tyxla]

Minor styling improvements to slug field - extending field to 100%, adding margin to properly center the field in the slug box.

[helen]

I'd rather get rid of that field/metabox, see #18523.

[tyxla]

As far as I understand, you are talking about removing the slug meta box in favor of the slug edit box in the Permalink section. This makes sense, but the Permalink section is not shown for non-public post types. So removing that meta box would prevent the user to manage the slug in non-public post types. And I've dealt with such cases in my experience - using non-public post types that are using the slug (and need a field to manage it). I'll post my opinion in #18523 for consideration.

[sabernhardt]

Editing the margin probably is too much for something that we wanted to remove, but I'll close this and reopen #16346 to discuss widening the field for as long as it is available.