<p>This is what I have, which works in IE7, but not in Firefox:</p>

<pre><code>@media screen { @import 'screen.css'; }
</code></pre>

<p>It works outside of the @media block in Firefox:</p>

<pre><code>@import 'screen.css';
</code></pre>

<p><strong>UPDATE:</strong>  </p>

<p>This works:</p>

<pre><code>@media screen { 

    .yui-d3f
    {
        border: 1px solid #999;
        height: 250px;
    }

}
</code></pre>

<p>What am I missing?</p>

Ok, so Firefox doesn't like the method I chose, favouring:
```
```
@import 'stylesheet.css' media_type;
```
```
But IE7 doesn't understand this method, but this could be good:
```
```
@import 'firefox-screen.css' screen;
@media screen { @import 'IE7-screen.css'; }
```
```