I need to set the width of textboxes as 80% of it's parent. So first I used

td input[type="text"]
{    
    width: 80%;
}

But it was not rendering properly if the input is the child of td. So, I used Css expressions

td input[type="text"]
{    
    width: expression(this.parentNode.offsetWidth*0.8);
}

It is working as I wanted in every browser except IE 6. Can anybody help me, where I am going wrong? I know that expressions are allowed in IE 6. So, is it the problem of using css expression or something to do offsetWidth.

Thanks in advance.