Is it possible to make input fields read-only through CSS?

With CSS only? This is sort of possible on text inputs by using user-select:none:

.print {
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;          
}

JSFiddle example.

It’s well worth noting that this will not work in browsers which do not support CSS3 or support the user-select property. The readonly property should be ideally given to the input markup you wish to be made readonly, but this does work as a hacky CSS alternative.

With JavaScript:

document.getElementById("myReadonlyInput").setAttribute("readonly", "true");

Edit: The CSS method no longer works in Chrome (29). The -webkit-user-select property now appears to be ignored on input elements.