diff --git a/app/operator_panel/index.php b/app/operator_panel/index.php
index ed26085388..de22e0d10f 100644
--- a/app/operator_panel/index.php
+++ b/app/operator_panel/index.php
@@ -145,6 +145,13 @@
$ws_client_hash = md5_file(__DIR__ . '/resources/javascript/websocket_client.js');
$lop_js_hash = md5_file(__DIR__ . '/resources/javascript/operator_panel.js');
+// Cache-busting hash for CSS
+ $operator_panel_css_file = $settings->get('theme', 'operator_panel_css_file', 'operator_panel.css');
+ $operator_panel_css_file = preg_replace('/[^a-z0-9_\-\.]/i', '', $operator_panel_css_file);
+ $operator_panel_css_file = realpath(__DIR__ . "/resources/css/$operator_panel_css_file");
+ $operator_panel_css_hash = md5_file($operator_panel_css_file);
+ echo "\n";
+
?>