I was able to set the border color using CSS in the bottom of our WP starter theme styles.css using the following command but the height and rows don't seem to work - can someone tell me the correct syntax (Note: I'm using the gf_right_half for the CSS class name:
body #gform_wrapper_11 .gform_body .gform_fields #field_11_8.gfield textarea {
border: 1px solid green;
width: 100%;
height: 5px !important;
rows: 5 !important;
}