Yi 2

Hi Sam,

Updated yi.html. yi.css and yi.scss.

I had some trouble with $color--black and $color --white.
I couldn't do @function for these two colors. It always gave me error message in terminal, and broke the website. When I used this valuable line "$color--black: adjust-color($color--primary, $hue:-132.47978, $saturation: -91.66667, $lightness: -35.88235);" , everything worked. So I greyed out @function line for black and white in .scss.

Could you please help me to check it out?
Thank you very much.