How to reduce height of trigger of editable combo

[wavel]

Using editable combo how to reduce height of trigger field of Editable combo

Do not want to change height in the third party css file.
I want to override css class .x-form-trigger height in jsp and change height to 15px
How Can I do it.


.x-form-field-wrap .x-form-trigger{
width:17px;
height:21px; ///Height of trigger
border:0;
background:transparent url(../images/default/form/trigger.gif) no-repeat 0 0;
cursor:pointer;
border-bottom: 1px solid #B5B8C8;
position:absolute;
top:0;
}


thanks:-?