here's how you refer to this:
document.form.textArea1.style.background = '#cccccc';
so you could do this: suppose you had element A, and if you typed something in it you wanted element B to go from grey to white
<input type="text" name="A" value="" onBlur="if(this.value <> ''){document.form.B.style.background = '#ffffff';}elseif(this.value ==''){document.form.B.style.background = '#cccccc';document.form.B.value='';}">
I'm not guaranteeing this code but it's close if not perfect, when you blur on a and it's blank, b goes blank and grey, if you blur on a and it's NOT blank, b goes white.
LMK if this works.
Sam Fullman
Compass Point Media