Added Chapter 11: Color/css/foreground-color.css
Added Chapter 11: Color/foreground-color.html
Added Chapter 11: Color/background-color.html
Added Chapter 11: Color/css/background-color.css
Added Chapter 11: Color/css/opacity.css
Added Chapter 11: Color/css/hsla.css
Added Chapter 11: Color/hsla.html
Added Chapter 11: Color/css/example.css
Added Chapter 11: Color/example.html