diff --git a/web/index.php b/web/index.php
index a716723..79d3abd 100755
--- a/web/index.php
+++ b/web/index.php
@@ -40,6 +40,13 @@ switch ($url[0]) {
             echo 'Invalid viewport format. Use WIDTHxHEIGHT (e.g., 1024x768)';
             exit;
         }
+        $vpParts = array_map('intval', explode('x', $viewport));
+        if ($vpParts[0] > 3840 || $vpParts[1] > 2160) {
+            header('HTTP/1.0 400 Bad Request');
+            echo 'Viewport exceeds maximum (3840x2160)';
+            exit;
+        }
+
         $js = $_REQUEST['js'] == 'false' ? false : true;
 
         $serverUrl = 'http://localhost:4444';
@@ -49,45 +56,34 @@ switch ($url[0]) {
         $capabilities = DesiredCapabilities::chrome();
         $capabilities->setCapability(\Facebook\WebDriver\Chrome\ChromeOptions::CAPABILITY, $options);
 
-        //disable javascript if $js is false
         if (!$js)
             $capabilities->setCapability('javascriptEnabled', false);
 
-
         $driver = null;
         $error = null;
         try {
-            $driver = RemoteWebDriver::create($serverUrl, $capabilities, 30000, 60);
+            $driver = RemoteWebDriver::create($serverUrl, $capabilities, 30000, 60000);
+            $driver->manage()->window()->setSize(new \Facebook\WebDriver\WebDriverDimension($vpParts[0], $vpParts[1]));
             $driver->get($target);
-            //hide scroll bars
             $driver->executeScript('document.body.style.overflow = "hidden";');
 
-            if ($viewport) {
-                $viewport = explode('x', $viewport);
-                $driver->manage()->window()->setSize(new \Facebook\WebDriver\WebDriverDimension($viewport[0], $viewport[1]));
-            } else {
-                $viewport = [1024, 768];
-                $driver->manage()->window()->setSize(new \Facebook\WebDriver\WebDriverDimension($viewport[0], $viewport[1]));
-            }
-            $viewportLabel = is_array($viewport) ? implode('x', $viewport) : (string) $viewport;
-            addToLog("$ip\tRequested $target with viewport " . $viewportLabel . " and js " . ($js ? 'enabled' : 'disabled'));
+            addToLog($ip . ' Requested ' . $target . ' viewport=' . $viewport . ' js=' . ($js ? 'enabled' : 'disabled'));
 
-            // take screenshot and send to user
             $screenshot = $driver->takeScreenshot();
             header('Content-Type: image/png');
             header('Content-Length: ' . strlen($screenshot));
             echo $screenshot;
         } catch (Exception $e) {
             $error = $e->getMessage();
-            addToLog("$ip\tRequested $target but resulted in error:\t" . $error);
+            addToLog($ip . ' Error requesting ' . $target . ': ' . $error);
         } finally {
-            if ($driver instanceof \Facebook\WebDriver\Remote\RemoteWebDriver) {
+            if ($driver instanceof RemoteWebDriver) {
                 try { $driver->quit(); } catch (Exception $q) {}
             }
         }
         if ($error !== null) {
             header('HTTP/1.0 500 Internal Server Error');
-            echo 'Error: ' . $error;
+            echo 'Screenshot failed';
         }
 
         break;