function getStyleSheetFile($deviceData)
{
    global $gadgetString;
    global $styleSheetFile;
    $styleSheetFile = STYLE_SHEET_MEDIA_QUERIES;
    // by default, fall back on media queries
    if (!isset($gadgetString)) {
        $gadgetString = getIdMyGadgetStringAllDevices($deviceData);
    }
    if ($gadgetString === "Desktop") {
        $styleSheetFile = STYLE_SHEET_DESKTOP;
    } else {
        if ($gadgetString === "Tablet") {
            $styleSheetFile = STYLE_SHEET_TABLET;
        } else {
            if ($gadgetString === "iPhone") {
                $styleSheetFile = STYLE_SHEET_APPLE_PHONE;
            } else {
                if ($gadgetString === "Android Phone" || $gadgetString === "Mobile Phone") {
                    $styleSheetFile = STYLE_SHEET_ANDROID_PHONE;
                }
            }
        }
    }
    return $styleSheetFile;
}
<!DOCTYPE html>
<html lang='en'>
<?php 
$pageTitle = basename($_SERVER['PHP_SELF'], '.php');
require_once 'Mobile-Detect/Mobile_Detect.php';
require_once '../../php/IdMyGadgetMobileDetect.php';
require_once '../all_detectors/getIdMyGadgetStringAllDevices.php';
require_once '../all_detectors/printStyleSheetLinkTags.php';
$debugging = FALSE;
$allowOverridesInUrl = TRUE;
// Needed for footer forms to work
$idMyGadget = new IdMyGadgetMobileDetect($debugging, $allowOverridesInUrl);
$idMyGadget->idMyGadgetDir = '../..';
$deviceData = $idMyGadget->getDeviceData();
$gadgetString = getIdMyGadgetStringAllDevices($deviceData);
?>

<head>
	<title><?php 
print $pageTitle;
?>
</title>
	<meta name="viewport" content="width=device-width, initial-scale=1.0" />
	<?php 
$styleSheetFile = printStyleSheetLinkTags($deviceData);
?>
</head>

<body>
<div id="container">
<h2><?php 
 /**
  * Constructor: for best results, specify a different gadgetDetector
  */
 public function __construct($gadgetDetectorString = null, $debugging = FALSE, $allowOverridesInUrl = TRUE)
 {
     //	error_log( 'Creating a base JmwsIdMyGadget object for detector "' . $gadgetDetectorString . '" - note we want to do this only once!' );
     require_once 'gadget_detectors/all_detectors/getIdMyGadgetStringAllDevices.php';
     if ($gadgetDetectorString === null) {
         $gadgetDetectorString = IdMyGadget::GADGET_DETECTOR_DETECT_MOBILE_BROWSERS;
     }
     $this->gadgetDetectorString = $gadgetDetectorString;
     if ($gadgetDetectorString === IdMyGadget::GADGET_DETECTOR_DETECT_MOBILE_BROWSERS) {
         global $usingMobilePhone;
         $fileToInclude = 'gadget_detectors/detect_mobile_browsers/php/detectmobilebrowser.php';
         $fileToCheck = $this->idMyGadgetDir . DIRECTORY_SEPARATOR . $fileToInclude;
         if (file_exists($fileToCheck)) {
             include_once $fileToInclude;
             // sets $usingMobilePhone global variable
         }
         include_once 'php/IdMyGadgetDetectMobileBrowsers.php';
         $this->idMyGadget = new IdMyGadgetDetectMobileBrowsers($debugging, $allowOverridesInUrl);
     } else {
         if ($gadgetDetectorString === IdMyGadget::GADGET_DETECTOR_MOBILE_DETECT) {
             $fileToInclude = 'gadget_detectors/mobile_detect/Mobile-Detect/Mobile_Detect.php';
             $fileToCheck = $this->idMyGadgetDir . DIRECTORY_SEPARATOR . $fileToInclude;
             if (file_exists($fileToCheck)) {
                 include_once $fileToInclude;
             }
             include_once 'php/IdMyGadgetMobileDetect.php';
             $this->idMyGadget = new IdMyGadgetMobileDetect($debugging, $allowOverridesInUrl);
         } else {
             if ($gadgetDetectorString === IdMyGadget::GADGET_DETECTOR_TERA_WURFL) {
                 $fileToInclude = 'gadget_detectors/tera_wurfl/Tera-Wurfl/wurfl-dbapi/TeraWurfl.php';
                 $fileToCheck = $this->idMyGadgetDir . DIRECTORY_SEPARATOR . $fileToInclude;
                 if (file_exists($fileToCheck)) {
                     include_once $fileToInclude;
                 }
                 include_once 'php/IdMyGadgetTeraWurfl.php';
                 $this->idMyGadget = new IdMyGadgetTeraWurfl($debugging, $allowOverridesInUrl);
             } else {
                 error_log('Warning: device detection has been disabled in the IdMyGadget administration console options.');
                 include_once 'php/IdMyGadgetNoDetection.php';
                 $this->idMyGadget = new IdMyGadgetNoDetection($debugging, $allowOverridesInUrl);
             }
         }
     }
     if ($this->idMyGadget !== null) {
         $this->idMyGadget->idMyGadgetDir = $this->idMyGadgetDir;
         if ($this->idMyGadget->isInstalled()) {
             $this->deviceData = $this->idMyGadget->getDeviceData();
             $this->gadgetString = getIdMyGadgetStringAllDevices($this->deviceData);
             if ($this->idMyGadget->detectorUsed !== IdMyGadget::GADGET_DETECTOR_NO_DETECTION) {
                 $this->detectionEnabled = TRUE;
             }
         } else {
             $this->gadgetString = self::GADGET_STRING_DETECTOR_NOT_INSTALLED;
         }
     }
     $this->gadgetDetectorStringChar = substr($this->gadgetDetectorString, 0, 1);
     // part of the sanity check string
     $this->gadgetStringChar = substr($this->gadgetString, 0, 1);
     // part of the sanity check string
     $this->initializeJQueryMobileVars();
 }