Apple changes not only the look of Control Center in iOS 11, it changes the behaviour of Wi-Fi and Bluetooth buttons on Control Center. In the past, when you tap to toggle off the Wi-Fi or Bluetooth button, iPhone completely shutdown the Wi-Fi or Bluetooth services. Not anymore.
In iOS 11, when you tap to off Wi-Fi from the Control Center, it simply just disconnect from the current Wi-Fi router. The Wi-Fi service remains active on the device. Similarly when you tap to toggle off the Bluetooth button on the Control Center, it only disconnects any connected Bluetooth devices.
To actually turn off Wi-Fi and Bluetooth services on your devices, you have to do so via the Settings app.