Improve admin user friendliness

[Ryan Allen]

​https://github.com/django/django/pull/1707

Links to the admin index and site index in the header
Green success messages
Tone down the red error messages
Min-width for date and time fields (could not read whole date in input box when clicking 'Today')
A handful of other subtle details

[Ryan Allen]

Errors

[Ryan Allen]

Successes

[Ryan Allen]

Link to Admin Home

[Ryan Allen]

Link to Site Home

[Tim Graham]

It's better not to include so many changes in one ticket. For example, the issue of linking the header has already been proposed in #13749.

I'm inclined to avoid changing colors at this time -- otherwise we'll end up having someone else come along and make different suggestions. I know a redesign or reskins of the admin has been proposed on django-developers in the past, but as far as I know there are no active efforts on this front.

If you could split the pull request into smaller parts (for example, the width changes that Marc said looked good) that will make it easier to review and merge.

[Ryan Allen]

For what it's worth, obviously design choices are a special case since everyone has their own idea of what's best. But isn't the whole point of open-source to have contributors come and make different suggestions? Django has an extraordinarily powerful backend but is falling behind on the frontend, where non-technical users are experiencing it. There are just a handful of styling updates in this patch, but they modernize the admin design immensely, while holding true to Django's personality. Could be a good start to reactivating those efforts from before.

Thanks -- I'll get to work splitting up the changes.

[Ryan Allen]

Changes have been split up into smaller pull requests:

​https://github.com/django/django/pull/1713 - min-width for date and time inputs
​https://github.com/django/django/pull/1715 - update admin alerts to appropriate colors
​https://github.com/django/django/pull/1712 - header and modules design improvements
​https://github.com/django/django/pull/1714 - link to site home in header if it exists
​https://github.com/django/django/pull/1710 - admin index link in header
​https://github.com/django/django/pull/1711 - admin/base.css cleanup (indentation, minor optimization)

[Tim Graham <timograham@…>]

In 259a6ea82cfb8bf242449666e4b643a19e54a423:

Added a link in admin branding block to admin index.

Refs #13749 and #21220.

[Tim Graham <timograham@…>]

In 3eab22a0452f976727ba21b4b6e25dabba85111e:

Added min-width for date and time inputs in admin.

refs #21220.

[Tim Graham <timograham@…>]

In 935001c4f1ab8660c76323854945e9e660514046:

Cleaned up admin CSS for consistency.

• header selected twice -merged
• match indentation throughout
• color names to hex

refs #21220.

[Tim Graham <timograham@…>]

In f719d4afc74e750b34247a574f800598c3daf1cc:

Updated admin alert colors

refs #21220.

[Tim Graham]

Closing this given that all pull requests have been merged.