Hi cfnet21,
I can not access your backend. However, I have checked and see that you can open the templates\ja_good\tpls\blocks\head.php file and find the line 43.
Replace this code:
<?php
// SYSTEM CSS
$this->addStyleSheet(JUri::base(true) . '/templates/system/css/system.css');
?>
With the following code:
<?php
if(version_compare(JVERSION,"4","lt")){
$this->addStyleSheet(JUri::base(true) . '/templates/system/css/system.css');
}
?>