Disable text input zoom

On some mobile browsers, when a text input is selected, the website is zoomed automatically:

The zooming is done by the browser and not by the app. This behavior can be disabled by adding the following meta tag on your theme:

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

Note: the important part is the maximum-scale=1 part. If the meta tag "viewport" already exists on your theme, you can simply add this part to the end.

To apply it to your own theme; navigate to Online Store > Themes,  [...] > Edit code:

Find the theme.liquid file:

Add or update the "viewport" meta tag: