[wp-trac] [WordPress Trac] #64418: Valid CSS is causing failure in the Additional CSS panel

[WordPress Trac]

#64418: Valid CSS is causing failure in the Additional CSS panel
--------------------------+---------------------
 Reporter:  drw158        |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  7.0
Component:  Customize     |     Version:  4.7
 Severity:  normal        |  Resolution:
 Keywords:  needs-patch   |     Focuses:  css
--------------------------+---------------------

Comment (by westonruter):

 The problematic code is [https://github.com/WordPress/wordpress-
 develop/blob/eda8d9d27b129ac48143af7d9c2df595dc172e44/src/wp-
 includes/customize/class-wp-customize-custom-css-setting.php#L166-L168
 located] in `WP_Customize_Custom_CSS_Setting::validate()`:

 {{{#!php
 <?php
 if ( preg_match( '#</?\w+#', $css ) ) {
         $validity->add( 'illegal_markup', __( 'Markup is not allowed in
 CSS.' ) );
 }
 }}}

 Clearly this is very naïve and it should be removed.

 Commenting out that logic allows the setting to save, but then the angle
 brackets get stripped out:

 {{{#!css
 @property --animate {
   syntax: "";
   inherits: true;
   initial-value: false;
 }
 }}}

 The problem then is inside `wp_custom_css_cb()`
 ([https://github.com/WordPress/wordpress-
 develop/blob/eda8d9d27b129ac48143af7d9c2df595dc172e44/src/wp-
 includes/theme.php#L1968-L1981 source]) because it runs the CSS through
 `strip_tags()`.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/64418#comment:2>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform