There are absolute url and relative url. In CSS, relative URLs are relative to the style sheet itself, not to the HTML document that uses the style sheet.
Example:
@import url(special/toppings.css);
Note that there cannot be a space between the url and the opening parenthesis:
body {background: url(https://www.pix.web/picture1.jpg);} /* correct */
body {background: url (images/picture2.jpg);} /* INCORRECT */
By Bryan Xu