 <p>With whichever of the two languages you'll be using to determine whether the user is logged in, create a conditional statement that adds a html class to the input field that alters it's width say .input-full and .input-partial</p> <pre><code>IF user is logged in SET class to input-full ELSE SET class to input-partial ENDIF </code></pre> <p>sorry for the psedo code, then have appropriate CSS for each.</p> <p>oooh, didn't see the CSS only, sorry. Without CSS3 and a disregard for IE I don't think you can do this with straight CSS.</p>