Remove default textarea padding

<textarea>s have a 2px padding on both Chrome & Firefox. <pre>s,
however, don't, which makes for miniscule text jumps between index.html
& paste.html.

templates/index.html

@@ -10,6 +10,7 @@
         background: none;
         border: none;
         outline: 0;
+        padding: 0;
 
         resize: none;
         overflow: auto;