MetaExtension viewport

Is used to give the browser instructions on how to control the page's scaling and dimensions.

Attention: Is essential for the use of media-queries in css!

Usage

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

content may be:

• width=device-width: Sets the pages width to the screen-size of the device
• initial-scale=1.0: Sets the initial zoom level (in this case to 1)
• user-scalable=no: Tells the browser if the user should be abled to scale a page or not. Is not reccommended and will be marked as a warning in W3 Validator since zooming in is an important accessibility feature, which is why it won't work in most browsers and is therefore marked as Unsupported.
• maximum-scale=3: Sets the maximum zoom level (In this case 3) Is not reccommended and will be marked as a warning in W3 Validator since zooming in is an important accessibility feature, which is why it won't work in most browsers and is therefore marked as Unsupported.

Read more at W3Schools (opens in a new tab) or at the W3 WAI (Web Accessability Iniative) (opens in a new tab).