I discovered a bug in modmat's sandbox.php when following the article, Giving WordPress Its Own Directory, where clicking Home will take you to the URL listed in Settings > General > WordPress address (URL), which may not display your WordPress homepage properly.
Locate the following code in wp-content/themes/modmat/functions/sandbox.php:
echo '><a href="' . get_settings('siteurl') . '">Home</a>';
And replace it with this line:
echo '><a href="' . get_option('home') . '">Home</a>';
Cheers!