How can I make the width of a textbox 100%?

How to make a width 100% text box. I add 100% or auto on settings but it dont' works.

I see that you are looking to force the width of your textbox to be 100%.

The existing size feature only adjusts the width based on a px value.

To make this happen on your form you need to use injected css or our form designer css helper.

Also, please see the example screenshots for comparison below.

Demo Form:

https://form.jotform.com/53204844392960? 

Here is the CSS CODE: 

#input_3 { width: 100%; }

Normal Textboxes:

Textbox 2 with Injected CSS to force 100%: (notice it's a tadbit longer than Textbox 1)

Textbox 2 again with Injected CSS to force % at 250% just to show you it's working:

¡It works perfectly! thank you KadeJM.