CSS - :-moz-only-whitespace
The :-moz-only-whitespace CSS pseudo-class matches an element that has no child nodes at all or empty text nodes or text nodes that have only white-space in them. Only when there are element nodes or text nodes with one or more characters inside the element, the element doesn't match this pseudo-class anymore.
Example
CSS
span:-moz-only-whitespace::before { background-color: lime; }
HTML
<span> </span>
Syntax
<var>span</var>:-moz-only-whitespace { style properties }
Description
The :-moz-only-whitespace CSS pseudo-class matches an element that has no child nodes at all or empty text nodes or text nodes that have only white-space in them. Only when there are element nodes or text nodes with one or more characters inside the element, the element doesn't match this pseudo-class anymore.
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/css/:-moz-only-whitespace