Using an external css in Flex 4

Question

I'm using the Flex 4 beta and the ability to load an external css seems to be broken. Running the code below shows no styling at all. Have I missed something?
components.MainPanel.as:
package components {
import flash.events.Event;
import flash.net.URLLoader;
import flash.net.URLRequest;
import flash.text.StyleSheet;
public class MainPanel extends Panel
    private var mainLabel:Label = new Label();
    private var label2:Label = new Label();
    public function MainPanel()
        super();
        var cssUrl:URLRequest = new URLRequest("css/style.css");
        var cssLoader:URLLoader = new URLLoader();
        cssLoader.addEventListener(Event.COMPLETE, cssLoaded);
        cssLoader.load(cssUrl);
    function cssLoaded(event:Event):void {
        var css:StyleSheet = new StyleSheet();
        css.parseCSS(URLLoader(event.target).data);
        mainLabel.styleSheet = css;
        mainLabel.htmlText = "Main Label";
        mainLabel.horizontalCenter = 0;
        mainLabel.verticalCenter = -350;
        mainLabel.setStyle("styleName", "h1");
        addElement(mainLabel);
        label2.htmlText="Sub-Label";
        label2.horizontalCenter="0";
        label2.verticalCenter="-300";
        addElement(label2);
css/style.css:
.h1 {     color:#ffe145;     font-family: Verdana;     font-size: 36;     font-style: italic;     font-weight: bold; }
app.mxml:
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/halo"
               xmlns:custom="components.*"
               minHeight="768"
               minWidth="1024"
               backgroundColor="#333399">
    <custom:MainPanel horizontalCenter="0" verticalCenter="0"/>
</s:Application>

Answer 1

Thanks for the quick response dj_page. I definitely expect compression when creating jpegs but this kind of shocked me especially since I was starting with a jpeg.
The pixel count difference is indeed the result of cropping so that's expected.
After some experimentation with exporting files as jpeg and then comparing them to the file created as a result of "Edit in..." it seems that it would take a quality setting of 60 in LR Export to create a file of the same size that's created by Edit In. That's lower than what I thought was the LR default of 75 and definitely produces visible degradation.
Maybe someone who uses Edit In... can either confirm that there's a problem (and hopefully a workaround) or that it must be something with my setup.