I'm going to extract background of some HTML files and replace them with new values.   

In order to control if **BODY** tag got background defined in its style as css i used below code:

```
foreach (HtmlNode bodyNode in doc.DocumentNode.SelectNodes("//body"))
{
  if (bodyNode.Attributes.Contains("style") && bodyNode.Attributes["style"].Value.Replace(" ","").Contains("background-image:url"))
  {
    //code to replace background-url
  }

}

```

my problem is how to retrive background-url value from such tag from style properties:

```
<body style="background-image: url('test/bg.jpg')" >

```

and replace it with new value like below:

```
<body style="background-image: url('new value')" >

```