Make sure math methods extraction checks for word boundaries

Otherwise, 'max' could be confused with 'minmax'

Fixes #356

Author: matthiasmullie

src/CSS.php

@@ -685,7 +685,7 @@ protected function stripWhitespace($content)
     protected function extractMath()
     {
         $functions = array('calc', 'clamp', 'min', 'max');
-        $pattern = '/('. implode('|', $functions) .')(\(.+?)(?=$|;|})/m';
+        $pattern = '/\b('. implode('|', $functions) .')(\(.+?)(?=$|;|})/m';
 
         // PHP only supports $this inside anonymous functions since 5.4
         $minifier = $this;

tests/css/CSSTest.php

@@ -833,6 +833,12 @@ public function dataProvider()
             '.space-x-4>:not([hidden])~:not([hidden]){--tw-space-x-reverse:0;margin-right:calc(1rem * var(--tw-space-x-reverse));margin-left:calc(1rem * calc(1 - var(--tw-space-x-reverse)))}',
         );
 
+        // https://github.com/matthiasmullie/minify/issues/356
+        $tests[] = array(
+            '.testclass{ grid-template-columns:minmax(0,1fr) minmax(0,1fr) minmax(0,1fr); }',
+            '.testclass{grid-template-columns:minmax(0,1fr) minmax(0,1fr) minmax(0,1fr)}',
+        );
+
         return $tests;
     }