Change $(this) css property 'of focus alone' on click of selectected textarea

Change $(this) css property 'of focus alone' on click of selectected textarea

I have html code something like this
<textarea class="new" id="1"></textarea>
<textarea class="new" id="2"></textarea>
Now How can I change its css property of 'focus' state alone
Original Css
.new{
height:60px;
}
.new:focus{
height:80px;}
Now when user clicks on textarea of id 1, the focus of that alone should
get changed,
$(this).css(height,'100px');
But the problem is , it changes the whole i.e. .new css property . Is that
possible to change property of $(this) with focus , something.....
Thanks for reading