Initialize repository with existing assets.
Rename `main.xht` to `index.xhtml`.

For greater compatibility.
Add shadows in textareas.

Correspondingly, darken the text so it doesn’t contrast too much with
the darker surroundings.
Remove autofocus from input textarea.

To make a better first impression, unmarred by whatever bounding box or
similar a browser may apply to indicate the selected element.
Add “SHA hash calculator” title header.
Add `main.xht` -> `index.xhtml` symbolic link.

For compatibility with prior installation(s) expecting `main.xht`.
Adjust textarea border-radii.

Set border-radius to 0 for bottom-right corners of textareas, so as to
not clash with browser-applied resize controls, and minorly adjust the
rest.