Weird Error Message

I’m using a modified version of Adelle on my blog, http://colleeniscreative.com/mommypanda. When WP updated, a bunch of the changes went away. (Womp womp) so I began the hunt for a new theme. I decided to try out Umbra, but when I do the live preview, I get this message:

Parse error: syntax error, unexpected T_SL in /home/content/59/3633259/html/mommypanda/wp-content/themes/umbra/inc/base-scss.php on line 8

Does anyone know what it means? What should I do to get the theme working?