2.1.8 [CSS-Level2-2009] Section 4.3.4, URLs and URIs
The specification states:
In order to create modular style sheets that are not dependent on the absolute location of a resource, authors may use relative URIs. Relative URIs (as defined in [RFC3986]) are resolved to full URIs using a base URI. RFC 3986, section 5, defines the normative algorithm for this process. For CSS style sheets, the base URI is that of the style sheet, not that of the source document.
All Document Modes (All Versions)
Cursor resource paths are relative to the path of document the rule is applied to, not that of the style sheet.