Textarea bottom margin

Suite and Optimus Suite 7
#1

I am trying to fill the entire extent of a form with a textarea.
Although padding is set to 0px, always remains a margin at the bottom of the form.
What am I doing wrong?

this the link to a snippet
https://snippet.dhtmlx.com/yx12xtvo

#2

these are default padding required for the spacing between controls.
You can avoid them with the following css:
https://snippet.dhtmlx.com/s9tcrpfn