I generally like to think that icon use should be handled as part of the CSS, as it's a design element and not part of the document semantics. Putting it in the

I generally like to think that icon use should be handled as part of the CSS, as it's a design element and not part of the document semantics. Putting it in the markup means that if the design is updated, the markup is still stuck with the old icon, which means it's more work to update the site.