I have the following CSS and HTML snippet being rendered.
If you pad and offset it like this:
textarea
{
border:1px solid #999999;
width:100%;
padding: 7px 0 7px 7px;
position:relative; left:-8px; /* 1px border, too */
}
the right side of the textarea perfectly aligns with the right side of the container, and the text inside the textarea aligns perfectly with the body text in the container... and the left side of the textarea 'sticks out' a bit. it's sometimes prettier.