Change color of one character in a text box HTML/CSS [duplicate]

You can’t do this with a regular <input type="text"> or <textarea> element, but with a normal element (like <div> or <p>) made contenteditable, you have all the freedoms of html/css formatting.

<div contenteditable>
    ST<span style="color: red">A</span>CK OVERFLOW
</div>

http://jsfiddle.net/jVqDJ/

The browser support is very good as well (IE5.5+). Read more at https://developer.mozilla.org/en-US/docs/Web/HTML/Content_Editable