viewport header code example
Example 1: meta name viewport
<meta name="viewport" content="width=device-width, initial-scale=1.0">
Example 2: html change viewport to smartphone size
<meta name="viewport" content="width=500, initial-scale=1">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="viewport" content="width=500, initial-scale=1">