It works for me, that is, I get a security error in the Error Console (Ctrl+Shift+J) 
Security Error: Content at http://perlmonks.com/?node_id=872091 may no
+t load or link to file:///C:/local.nonsense.css.

[download]
I say its a good idea to not allow websites to access random files on my computer.

The generic way to do this is with Greasemonkey plugin (and http://userscripts.org/)

You could also do it with a bookmarklet, but that means an extra click 

javascript:(function(){    function addRawCss(styles){ var newSS; if(d
+ocument.createStyleSheet){ document.createStyleSheet("javascript:'" +
+ styles.replace(/'/g,"\\'") + "'"); }else{ newSS=document.createEleme
+nt("link"); newSS.rel="stylesheet"; newSS.href="data:text/css,"+escap
+e(styles); document.documentElement.childNodes[0].appendChild(newSS);
+ } } addRawCss("body { color: yellow !important; background-color: bl
+ack !important; }");    })()

[download]

In reply to Re: PM Stylesheet on local filesystem? by Anonymous Monk
in thread PM Stylesheet on local filesystem? WORKS! by roboticus

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