CSS3 Button

I need some help styling this button. The thing that is throwing me off is the darker color on the outer border. I would like to create the entire thing using css with only a background image for a slight gradient. My first thought was to have the border color be the 2px lighter orange color border and have a 1px outline for the darker orange color but using border-radius to round the corners does not round the outline color. Any ideas on how I can achieve this? I know that firefox has the ability for multiple border colors using -moz-border-colors, but I would like to find a way that works in the majority of the newer browsers. Here is the code I have so far...

html
<div class="btn_order_wrap"><a class="button_order" href="#">Add to Cart</a></div>

css

a.button_order {
border:.2em solid #febf4d;
background:#fba213;
font-family:"Trebuchet MS", Helvetica, Arial, sans-serif;
font-size:1.4em;
font-weight: bold;
text-transform: uppercase;
color:#fff;
padding:3px 14px;
text-decoration:none;
line-height:1;
border-radius: 8px;
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
}

I added a class to the div and added this..

.btn_order_wrap {
background:#e26703;
float:left;
padding:.6em 0;
line-height:1;
border-radius: 8px;
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
}

which works somewhat but seems like there would be a better way and it doesn't resize properly when text is resized.