Add a viewport meta tag to the document head to set the width of the layout viewport equal to the width of the device and set the initial scale of the viewport to 1.0.

<meta name="viewport" content="width=device-width, initial-scale=1">

<meta name="viewport" content="width=device-width, initial-scale=1.0">

<meta name="viewport" content="width=device-width, initial-scale=1.0" />