<meta name="viewport" content="width=device-width, initial-scale=1">
The tag causes browsers to display the page in the size of the device pixels and not to try to scale down a large page. Peter Paul Koch explains the connections excellently.
In some projects it is necessary to use the other specifications like user-scalable, minimum-scale and maximum-scale.
<link href="styles.css" rel="stylesheet">
The specification of the type attribute (type=”text/css”) is not necessary, since it is only a hint for the browser which MIME type to expect for the external resource.
It is ultimately the resource itself that determines which content type it returns. The browser then decides whether it is compatible with the link type stylesheet and is taken into account in rendering.
The end tag must not be omitted for script.