There is no function in XSLT that can return the value of the current font-size, but
there is in XSL-FO. The distinction is that XSLT functions are processed by the XSLT
processor such as Saxon or xsltproc, and XSL-FO functions are processed by the XSL-FO
processor such as FOP or XEP. The XSLT processor does not know what the "current"
font-size is, but the XSL-FO processor does.
Depending on your processor, it may support the inherited-property-value() function
described in the XSL standard. Since FOP 0.95 claims to support it, I suspect most do.
See:
http://www.w3.org/TR/xsl/#d0e5961Bob Stayton
Sagehill Enterprises
bobs@sagehill.net