[wp-trac] [WordPress Trac] #35229: Stop generating `wp-admin.min.css`

[WordPress Trac]

#35229: Stop generating `wp-admin.min.css`
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 Reporter:  dd32            |      Owner:
     Type:  enhancement     |     Status:  new
 Priority:  normal          |  Milestone:  4.5
Component:  Script Loader   |    Version:
 Severity:  normal          |   Keywords:  has-patch
  Focuses:  administration  |
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 Currently WordPress generates and ships relatively large 235K `wp-
 admin.min.css` and `wp-admin-rtl.min.css` files which are created from
 source files which we also ship.

 I'd like to propose that we stop generating these files, and instead rely
 upon `load-styles.php` instead  to combine them.

 My main reason is that I'd love for commits such as [35896] not to cause
 510KB of CSS to require be shipped to end users (That's the two 235K wp-
 admin files, plus dashboard.css/rtl). Instead, we'd only have to ship the
 4 dashboard.css files which is around 72K.

 Package size for regular releases won't be changed significantly, full
 package sizes would increase by 40K as we'd no longer get the benefit of
 the CSS minification process combining some CSS rules which are currently
 in separate files. (Currently wp-admin/css is 2,240KB and would be 2,280KB
 after this proposal)

 We'd still need to generate `wp-admin.min.css` and friends I guess for
 those who include it directly.

 Attached is a patch which does:
  * Alters the Gruntfile to just create minified versions of all wp-
 admin/css files
  * Creates `wp-admin.min.css`, `wp-admin-rtl.css`, and `wp-admin-
 rtl.min.css` manually (ie. not through cssmin) as we only need to do
 string replacements on the contents.
  * Adds all the individual `wp-admin.css` `@import`s to `script-
 loader.php`
  * Allows for `load-styles.php` to accept `load[]` like `load-scripts.php`
 to work around long-query-string limitations on some servers

 The only real downside of doing this is that we're effectively shifting
 from pre-compute to on-demand concatenation, not a huge deal IMHO as we
 cache the output of `load-styles.php` for 1 year already.
 It also shows how much needless CSS we load on all admin pages.

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Ticket URL: <https://core.trac.wordpress.org/ticket/35229>
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