How to inject CSS in WebBrowser control?

As per my knowledge,there is a way to inject javascript into the DOM. Below is the sample code that injects javascript with the webbrowser control:

HtmlElement head = webBrowser1.Document.GetElementsByTagName("head")[0];
HtmlElement scriptEl = webBrowser1.Document.CreateElement("script");
IHTMLScriptElement element = (IHTMLScriptElement)scriptEl.DomElement;
element.text = "function sayHello() { alert('hello') }";
head.AppendChild(scriptEl);
webBrowser1.Document.InvokeScript("sayHello");

Is there an easier way to inject css into the DOM?

paracycle

I didn't try this myself but since CSS style rules can be included in a document using the <style> tag as in:

<html>
<head>
<style type="text/css">
    h1 {color:red}
    p {color:blue}
</style>
</head>

you could try giving:

HtmlElement head = webBrowser1.Document.GetElementsByTagName("head")[0];
HtmlElement styleEl = webBrowser1.Document.CreateElement("style");
IHTMLStyleElement element = (IHTMLStyleElement)styleEl.DomElement;
IHTMLStyleSheetElement styleSheet = element.styleSheet;
styleSheet.cssText = @"h1 { color: red }";
head.AppendChild(styleEl);

a go. You can find more info on the IHTMLStyleElement here.

Edit

It seems the answer is much much simpler than I originally thought:

  using mshtml;

  IHTMLDocument2 doc = (webBrowser1.Document.DomDocument) as IHTMLDocument2;
  // The first parameter is the url, the second is the index of the added style sheet.
  IHTMLStyleSheet ss = doc.createStyleSheet("", 0);

  // Now that you have the style sheet you have a few options:
  // 1. You can just set the content as text.
  ss.cssText = @"h1 { color: blue; }";
  // 2. You can add/remove style rules.
  int index = ss.addRule("h1", "color: red;");
  ss.removeRule(index);
  // You can even walk over the rules using "ss.rules" and modify them.

I wrote a small test project to verify that this works. I arrived at this final result by doing a search on MSDN for IHTMLStyleSheet, upon which I happened across this page, this page and this one.

For me it seemed to be as simple as setting my style first in the DocumentText. Obviously not best practices but it works for simple CSS.

webBrowser1.DocumentText = "<style> " +
                                 "body { " +
                                    "font-family: Algerian; " +
                                  "} " +
                            "</style> "+
                            "<a href='https://www.google.ca'>Test</a>";

来源：https://stackoverflow.com/questions/5496549/how-to-inject-css-in-webbrowser-control

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