How do I make a WebKit WebView use a CSS style sheet?

Question

I made an html wich links to a CSS file, open it in browsers, and the styles show correctly.
Then I load it in a WebView and the styles don't show.
I even tried to insert a <link> into the DOM from Objective-C, which is my ultimate goal, but neither worked.
Do I have to enable CSS on the webView somehow?

edit:
the CSS include in the html:
<link rel='StyleSheet' href="file://localhost/Users/petruza/Source/Scrape/build/Debug/Scrape.app/Contents/Resources/Scrape.css" type="text/css" >

the CSS inserted in the DOM: (I checked and it does get inserted)

NSURL *cssUrl = [[NSBundle mainBundle] URLForResource:@"Scrape.css" withExtension: nil];

DOMDocument* dom = [[web mainFrame] DOMDocument];

[window setTitleWithRepresentedFilename: lastRunScript];

DOMElement* link = [dom createElement:@"link"];

[link setAttribute:@"rel" value:@"StyleSheet"];
[link setAttribute:@"type" value:@"text/css"];
[link setAttribute:@"href" value: [cssUrl absoluteString]];
    
DOMElement* head = (DOMElement*) [[dom getElementsByTagName:@"head"] item:0];
DOMElement* headFirstChild = head.firstElementChild;

if( headFirstChild )    
    [head insertBefore:link refChild:(DOMNode *)headFirstChild];    
else
    [head appendChild:(DOMNode *)link];

edit2:
Same exact html shown in my WebView and in Safari:

Answer 1

You might need to include an html <base> element to tell the webview where it shoul be looking for the css files.

Answer 2

Another alternative would be to use the user stylesheet preference of the WebView:

WebView* webView = /* snip */;
webView.preferences.userStyleSheetEnabled = YES;
webView.preferences.userStyleSheetLocation = [NSURL fileURLWithPath:@"my/stylesheet.css"];

Assuming that the style data can be reached with an URL, this is probably the simplest way to do it.