Creating a colored line across the size of the window?

How would I do this? The subject isn't very explained, so for an example: the black line at开发者_如何学Python the top of the footer.

Thanks!

#footer {
    width: 100%;
    height: 200px;
    border-top: 1px solid #000;
}

Do you mean <hr />?

You can use CSS to set the colour and size, e.g.

hr {
    height:25px;
    background-color: #00FF00;
    border:0;
}