The new units – vw, vh, vmin, and vmax - work similarly to existing length units like px or em, but represent a percentage of the current browser viewport.

External demo page

Here is some examples Neon Glow with pure CSS

External demo page

How To Get Thumbnails from Youtube Videos

Simply add this code inside HEAD tag.

<meta name="theme-color" content="#ff6600" />

This line is a HTML meta tag used by Google Chrome on Android to change color of address bar in mobile browser. The content field has the hex code for the color you want to use as theme color.