How to add a .css to a .cshtml

I'm a complete HTML/CSS novice and I am trying to get a .cshtml file to use some basic CSS I wrote. What code do I need to put in my .cshtml to get it to use the CSS file?

Edit: This is the code in my .css file. It is intended to style my div with the id of "comment_box1", but even after following the answer, it's not working. Any idea what's wrong?

.comment_box1 {
    background-color: #C8E0E8; 
    width: 830px; 
    height: 180px; 
}

Solution

Here is the basic option - you add a style tag to the <head> of your document...

<link rel="stylesheet" href="app.css" type="text/css" />

If you are using bundles, you place the bundle there instead:

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

And finally, if you are using a master layout, that's the best place to put this as it will then apply to all your pages.

Update

If you are targeting an id, you use #, rather than the dot, which is for a class.

#comment_box1
{
background-color: #C8E0E8; 
width: 830px; 
height: 180px; 
}