diff --git a/lib/inliner.php b/lib/inliner.php
index d10154f..7342400 100644
--- a/lib/inliner.php
+++ b/lib/inliner.php
@@ -11,9 +11,16 @@ function inlineLocalStylesFromHref($inputString) {
 
         $cssContent = preg_replace_callback('/url\(["\']?(\/.*?|.*?)["\']?\)/i', function($urlMatch) use ($cssDir) {
             $url = $urlMatch[1];
-            $absolutePath = $cssDir . '/' . $url;
-            $relativePath = ltrim(substr($absolutePath, strlen($_SERVER['DOCUMENT_ROOT'])), '/');
-            return 'url("' . $relativePath . '")';
+
+            // Check if the URL starts with any protocol or //
+            if (!preg_match('/^([a-zA-Z]+:)?\/\//', $url)) {
+                $absolutePath = $cssDir . '/' . $url;
+                $relativePath = ltrim(substr($absolutePath, strlen($_SERVER['DOCUMENT_ROOT'])), '/');
+                return 'url("' . $relativePath . '")';
+            } else {
+                // If the URL starts with a protocol or //, leave it unchanged
+                return 'url("' . $url . '")';
+            }
         }, $cssContent);
 
         // Minify the CSS content