I’m using the Date Picker from the Telerik MVC library. It appears and works fine in Firefox and IE8+ in standards mode.

In IE6, IE7, and IE8 in Quirks or IE7 Standards modes the input field is displayed, but not the calendar icon.

I think I’ve narrowed it down to a problem rendering the span that contains the icon. The HTML for this span is:
<span class="t-icon t-icon-calendar" title="Open the calendar">Open the calendar</span>
and the CSS applied to the span is:
The problem seems to be that the span is being rendered with width and height of 0px, regardless of what’s specified in the CSS. Why is this happening, and what can I do to fix it?
I’ve tried setting font-size and line-height to 12px, but it didn’t help.
Answer Update
It turns out that the styling on the span wasn’t the problem at all. I had some styling on the input element (float: left) which caused the span containing the image to end up behind the input.
It turns out that the styling on the span wasn’t the problem at all. I had some styling on the input element (float: left) which caused the span containing the image to end up behind the input.
I’ve added this as an update to the question also.