I'm having a trouble with to modify the size of text box.

I'm using DNN 7 ver.

Will you help me out with problems as follow:

1. Rich Text(Html) box
I could modify text box size with Html
but i can not modify the text box size with Plain text box.

Is there a way to modify the size of Plain text box? i mean, make it a bigger and wider.

2. text with multiline

I could changed the width and height of text box by using "CSS Style"

but, could not make it work as multiline text box

Is there a way to modify the size of text?

In advance, have a great weekend?