view port

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

initial-scale indicate relationship between device independent pixel and css pixel.

<meta name="viewport" content="width=360,initial-scale=1">

prevent image overflow content

img, embed, object, video {
  max-width: 100%
}

example

<img id="owl">
#owl {
 width: 640px;
 max-width: 100%;
}

CSS/Properties
https://www.w3.org/community/webed/wiki/CSS/Properties

nav a, button {
min-width: 48px;
max-height: 48px;
}