debugged introduction section, resized background image, and added comments
changed class names to half watch from half-watch, therefore making 2 separate classes. removed paragraph tags around watch the video text. now not working as well
debugged following lesson stylesheet through end of buttons. now not working as nicely. added comments to explain and commented out original code
fixed to look like lesson doc, kept original code in comments
fixed some scrolling issues, corrected end part to look like lesson css