From 917a01df1ea4215b68f7d19580ba0c044627ecf4 Mon Sep 17 00:00:00 2001
From: Alain Schlesser <alain.schlesser@gmail.com>
Date: Tue, 2 Jun 2020 07:52:28 +0200
Subject: [PATCH] Only use 'all and...' in conjunction with 'not'

---
 lib/optimizer/src/Transformer/ServerSideRendering.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/optimizer/src/Transformer/ServerSideRendering.php b/lib/optimizer/src/Transformer/ServerSideRendering.php
index 99c17cad9d3..8e9482889b2 100644
--- a/lib/optimizer/src/Transformer/ServerSideRendering.php
+++ b/lib/optimizer/src/Transformer/ServerSideRendering.php
@@ -1023,7 +1023,9 @@ private function extractMediaAttributeCss(Document $document, DOMElement $elemen
         $attributeValue = preg_replace('/^not\s+/i', '', $attributeValue, 1, $notFound);
         $not            = $notFound ? '' : 'not ';
 
-        if ($attributeValue[0] === '(') {
+        if ($attributeValue[0] === '(' && ! $notFound) {
+            // 'not' can only be used with a media type, so we use 'all' as media type if it is missing.
+            // See quirksmode.org/blog/archives/2012/11/what_the_hells.html#c15586
             $attributeValue = 'all and ' . $attributeValue;
         }