diff --git a/core/lib/Drupal/Core/Asset/CssOptimizer.php b/core/lib/Drupal/Core/Asset/CssOptimizer.php
index baa2de4..2b78011 100644
--- a/core/lib/Drupal/Core/Asset/CssOptimizer.php
+++ b/core/lib/Drupal/Core/Asset/CssOptimizer.php
@@ -50,8 +50,9 @@ protected function processFile($css_asset) {
     // Store base path.
     $this->rewriteFileURIBasePath = $css_base_path . '/';
 
-    // Anchor all paths in the CSS with its base URL, ignoring external and absolute paths.
-    return preg_replace_callback('/url\(\s*[\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\s*\)/i', array($this, 'rewriteFileURI'), $contents);
+    // Anchor all paths in the CSS with its base URL, ignoring external,
+    // absolute, and SVG (#) paths.
+    return preg_replace_callback('/url\(\s*[\'"]?(?![a-z]+:|\/+|\#+)([^\'")]+)[\'"]?\s*\)/i', array($this, 'rewriteFileURI'), $contents);
   }
 
   /**
@@ -143,8 +144,8 @@ protected function loadNestedFile($matches) {
 
     // Alter all internal _url() paths. Leave external paths alone. We don't need
     // to normalize absolute paths here (i.e. remove folder/... segments)
-    // because that will be done later.
-    return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)([^\'")]+)([\'"]?)\s*\)/i', 'url(\1' . $directory . '\2\3)', $file);
+    // because that will be done later. Also ignore SVG paths (#).
+    return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+|\#+)([^\'")]+)([\'"]?)\s*\)/i', 'url(\1' . $directory . '\2\3)', $file);
   }
 
   /**
diff --git a/core/modules/color/color.module b/core/modules/color/color.module
index 92e2136..4c99c98 100644
--- a/core/modules/color/color.module
+++ b/core/modules/color/color.module
@@ -491,8 +491,9 @@ function color_scheme_form_submit($form, FormStateInterface $form_state) {
       // off the name of the file at the end of the path.
       $css_optimizer->rewriteFileURIBasePath = base_path() . dirname($paths['source'] . $file) . '/';
 
-      // Prefix all paths within this CSS file, ignoring absolute paths.
-      $style = preg_replace_callback('/url\([\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\)/i', array($css_optimizer, 'rewriteFileURI'), $style);
+      // Prefix all paths within this CSS file, ignoring external, absolute, and
+      // SVG (#) paths.
+      $style = preg_replace_callback('/url\([\'"]?(?![a-z]+:|\/+|\#+)([^\'")]+)[\'"]?\)/i', array($css_optimizer, 'rewriteFileURI'), $style);
 
       // Rewrite stylesheet with new colors.
       $style = _color_rewrite_stylesheet($theme, $info, $paths, $palette, $style);