how to show website with full width on mobile devices

You could try to add this in your page head:

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

This will attempt to make the browser display the page at full-width.

Put the meta tag in the head

<head>
    <title>My Website</title>
    <meta name="viewport" content="user-scalable = no">
</head>

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