How to increase the textbox width in matrix field?

I need the text box to fill the last column that reads, "What happened to the pet? If Deceased, what was their age and cause of death?". How do I do that? Thanks you. 

This is fully possible with some conditional logic

I called the textbox "Value" and the Table "Table":

You can see it working from this picture:

My demo form URL:

https://form.jotformpro.com/71625215911956 

Unfortunately this doesn't seem to solve my issue. I just need the text box width to fill the entire column (cell) as it does in the first 2 columns. It's just a matter increasing the text box width. 

Hello,

Please inject the following custom css code in your form to increase the textbox width of matrix field:

li#id_28 .form-textbox {

    width: 90%;

}

The following guide should help you how to inject custom css code in form:  https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

Hope this helps.

Do get back to us if you have any questions.

Thank you!