I have a custom theme with just a name in its `style.css`. I've activated it in admin which shows it just fine. 

In the `index.php` just `<?php wp_head(); ?>` and it doesn't output the line that is supposed to include my main stylesheet `style.css`:

    <link rel='stylesheet' id='my-theme'  href='~/wp-content/themes/my-theme/style.css' type='text/css' media='all' />

It prints out all the other stuff ***but*** that line! What would make it not print out my default stylesheet inclusion line?