Question: When I use different layouts to support different screens , should I use dp or px .

Answer: 
yes @levib answer is short and correct one to use. Another alternative is that you can use slideUp() and slideDown() functions.

```
$(".fold_reply").click(function() {

    if ($('.reply').css('display', 'none')) {
        $(".reply").slideDown("slow");
    }
    else {
        $(".reply").slideUp("fast");
    }

});​

```
Use the jQueryUI version of `toggle()` since you seem to be using a jQuery UI effect

**.toggle( effect [, options ] [, duration ] [, complete ] )**

Reference: <http://api.jqueryui.com/toggle/>

```
$(".fold_reply").click(function() {
     $(".reply").toggle("fold",  500);
})

```