How to fix the size of div?

Hi all,
I used the form as hidden elements.
if user selects option from select box,related to that another select box will shown dynamically, to choose another option…

Now the problem is,
the hidden item is shown properly, but the div is stretching both sides of form(top & bottom), while this is showing…

why?

how to fix it.

Thanking you…

This is actually just a lack of CSS not PHP. Could you please clarify whats wrong with the display again. I was a little confused.

Thanks for your reply,

div tag i used in the table that to in one column…
in this column, i used to display the form with some select boxes…
based on selection of first one, it will shown the another select box dynamically, related to first one…
At the time of displaying the second one, the div height is increasing…
why?