Here's another possible method, this one using the HTML5 canvas element to draw an 'x' over the textarea.
Since I started working on it a bunch of other, answers popped up, some of them pretty similar. Lots of options to go with!
I place the textarea directly on top of the canvas (of the same size), then use rgba() with alpha 0 on the background of the textarea to make the background transparent so you can see the canvas underneath.
Looking through these though, I'm inclined to feel like the background image solution suggested by @Ragnarokkr and sussed out by @kalpesh patel may be the simplest solution, if executed right.
The code for mine:
HTML:
<canvas id="myCanvas" width="200" height="100"></canvas>
<textarea id="myTextArea"></textarea>
JS:
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.strokeStyle="red";
ctx.moveTo(0,100);
ctx.lineTo(200,0);
ctx.stroke();
ctx.moveTo(0,0);
ctx.lineTo(200,100);
ctx.stroke();
CSS:
html, body {
margin: 0;
padding: 0;
}
#myCanvas {
padding: 0;
margin: 0;
width: 200px;
height: 100px;
}
#myTextArea {
position: absolute;
left: 0px;
right: 0;
height: 102px;
width: 202px;
background: rgba(255,255,255,0);
padding: 0;
margin: 0;
}