<?php
$filename = "style.css";
$handle = fopen($filename, "r");
$contents = fread($handle, filesize($filename));
echo "
		<form method=\"post\" action=\"\">
			<textarea cols=\"30\" rows=\"5\" name=\"test\">{$contents}</textarea>
			<input type=\"submit\" name=\"update\" value=\"ערוך\" />
		</form>
	";
	if(isset($_POST['update'])) {
		file_put_contents($handle, $_POST['test']);
	}
?>