Check out example codes for "responsive meta tag". It will help you in understanding the concepts better.

Code Example 1

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

Code Example 2

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

Code Example 3

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

Code Example 4

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

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