How to include CSS styles inline in Razor view?

问题

I am using Postal to render MVC Razor views and send them via email. I have a custom CSS that I have defined specifically for the email views. Currently I am including them as follows:

@Styles.Render("~/Content/EmailStyles.css")

However, this only includes the relative link to the stylesheet, which will not work in an email:

<link href="/Content/EmailStyles.css" rel="stylesheet"/>

I want to include the stylesheet inline so that it functions properly in the email. What is the best way to render the contents of a file-based resource within an MVC view?

回答1:

I guess you will need to have a custom helper for that. On top of my head, there is no such a method to render the css path including the absolute path of the website.

e.g. http:www.example.com/css/EmailStyles.css

回答2:

I had the same question myself, and came across Premailer.Net. It looks like the library you need. Here's what you'd have to do:

Create an extension method to help you embed your CSS into your page; there's an answer on a question on how to embed HTML in a Razor view that should help you. I've modified it for embedding CSS:

public static class HtmlHelpers
{
    public static MvcHtmlString EmbedCss(this HtmlHelper htmlHelper, string path)
    {
        // take a path that starts with "~" and map it to the filesystem.
        var cssFilePath = HttpContext.Current.Server.MapPath(path);
        // load the contents of that file
        try
        {
            var cssText = System.IO.File.ReadAllText(cssFilePath);
            var styleElement = new TagBuilder("style");
            styleElement.InnerHtml = cssText;
            return MvcHtmlString.Create(styleElement.ToString());
        }
        catch (Exception ex)
        {
            // return nothing if we can't read the file for any reason
            return null;
        }
    }
}

Then in your Razor template, just go:
```
@Html.EmbedCss("~/Content/EmailStyles.css")
```
to embed your CSS text.
Install the Premailer.Net package in your project; you can get it through NuGet.
Render your Razor view into a string (I guess that's what Postal is for in your process? I believe RazorEngine can also do that).

Run the string through Premailer.Net:

PreMailer pm = new PreMailer();
string premailedOutput = pm.MoveCssInline(htmlSource, false);

Send as an e-mail!

I've been using this technique in production for a while now, and it seems to be working quite well.

Edit: Remember that styles on pseudo-elements can't be inlined because they don't exist in the markup. I've also noticed the odd little bug in Premailer.Net -- I think their specificity and cascade rules aren't perfectly conformant. Still, it's pretty good and it's one more piece of code I didn't have to write!

回答3:

Upvoted Paul d'Aoust's answer, but I found this version of his helper method to work a little better for me (wouldn't try to encode things like quotes in the CSS):

public static class CssHelper
{
  public static IHtmlString EmbedCss(this HtmlHelper htmlHelper, string path)
  {
    // take a path that starts with "~" and map it to the filesystem.
    var cssFilePath = HttpContext.Current.Server.MapPath(path);
    // load the contents of that file
    try
    {
      var cssText = File.ReadAllText(cssFilePath);
      return htmlHelper.Raw("<style>\n" + cssText + "\n</style>");
    }
    catch
    {
      // return nothing if we can't read the file for any reason
      return null;
    }
  }
}

来源：https://stackoverflow.com/questions/14298604/how-to-include-css-styles-inline-in-razor-view

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asp.net-mvc

razor

asp.net-mvc-4

postal