Mixed content error in images,css,js after implementing SSL – Magento

Step: 1

system > Configuration > web > Use Secure URLs in Frontend > yes

Step 2: Put below code in magento index.php file in root folder

/*Block of code for https*/
foreach (array(
    'SERVER_PORT' => 443,
    'HTTP_X_FORWARDED_PROTO' => 'https',
    'HTTP_CF_VISITOR' => '{"scheme":"https"}'
    ) as $key => $value) 
{
    if (isset($_SERVER[$key]) && $_SERVER[$key] == $value) {
        $_SERVER['HTTPS'] = 'on';
        break;
    }
}