I do not know why it fell into the base 5, maybe this is a mistake!
It sets a browser window for browser layouts relative to which CSS ads are calculated, such as width: 20%, to the width of the device.
(By the way, Opera suggested moving this functionality to full CSS, which in general seems like a good idea. But at the moment they are stuck with an HTML tag.)
Typically, the layout view format takes a width that the provider has decided optimally for viewing desktop sites. By setting the meta-viewport to the width of the device, you will be sure that the width of your sites is optimized so that the device is viewed.
You can also use media queries.
Here you can clearly read http://tech.bluesmoon.info/2011/01/device-width-and-how-not-to-hate-your.html
chinmayahd
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