fixes

vendor/sabberworm/php-css-parser/src/Property/KeyframeSelector.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Sabberworm\CSS\Property;
+
+class KeyframeSelector extends Selector
+{
+    /**
+     * regexp for specificity calculations
+     *
+     * @var string
+     */
+    const SELECTOR_VALIDATION_RX = '/
+    ^(
+        (?:
+            [a-zA-Z0-9\x{00A0}-\x{FFFF}_^$|*="\'~\[\]()\-\s\.:#+>]* # any sequence of valid unescaped characters
+            (?:\\\\.)?                                              # a single escaped character
+            (?:([\'"]).*?(?<!\\\\)\2)?                              # a quoted text like [id="example"]
+        )*
+    )|
+    (\d+%)                                                          # keyframe animation progress percentage (e.g. 50%)
+    $
+    /ux';
+}