When structuring your markup there are many paths you can choose to reach the same goal. Most of the times it's a matter of preferences which element you wish to apply on a specific spot. I have my own personal preferences. One of them is preferring BUTTON over INPUT type="submit" elements. Why? Well W3C says it "Buttons created with the BUTTON element function just like buttons created with the INPUT element, but they offer richer rendering possibilities".

It's the rendering that I am after. You can easily apply image replacement techniques to buttons and make your form look good. Most interesting feature is that BUTTON element may have content. I will use that possibility in this tutorial.

So, the goal is to create and style button that can handle variable length so there is no need for later interventions. We'll treat button element as a container and add some markup.

Take a look at the demo | Download zip file

HTML

Here it is:

<button><span><em>Button text</em></span></button>

This is a valid code, and it gives us a lot to work with.

Please note, I am using two child elements instead of only one because I couldn't get rid of some paddings that button preserved. If anyone succeeds in styling with one child element only, please let me know :)

Concept

This concept is probably familiar to you from various navigation tab styling techniques. We have one long background image:

This one is 550px wide. I believe that is more than sufficient for buttons :)
So, we apply this image as a background image of a top element (in this case SPAN), place it to top left and add some left padding. Nested element (in this case EM) have the same background image but placed to top right and with right padding. As the content text grows so will the button.

Height of the button is fixed in my example but you can use similar technique and some more markup and place the same background image to all 4 corners.
To make sure that the text is vertically centered I use line-height property.

CSS

button{
	border:none;
	background:none;
	padding:0;
	margin:0;
	width:auto;
	overflow:visible;					
	text-align:center;	
	white-space:nowrap;	
	height:40px;
	line-height:38px;			
	}

Resetting button's default styling.

button span, button em{
	display:block;
	height:40px;
	line-height:38px;			
	margin:0;
	color:#954b05;
	}

Setting child elements. Note that value of height property is different than line-height. That's because I have 2px shadow at the bottom. Line-height vertically centers the text within the button graphic, shadow is excluded.

button span{
	padding-left:20px;
	background:url(bg_button.gif) no-repeat 0 0;
	}	
button em{
	font-style:normal;
	padding-right:20px;
	background:url(bg_button.gif) no-repeat 100% 0;
	}

Setting backgrounds and paddings for both child elements.

As I mentioned earlier, it would be more elegant if I could use BUTTON and SPAN only, but I couldn' t get rid of BUTTON paddings.