At this point in the process of designing and developing my website I have one single external stylesheet file that helps me to style the pages. In order to have one CSS file, I detect the media type and apply the specific styles. For screen I have one set of styles and for print I have another set of styles.
For assignment 6 I also created one CSS transformation and two CSS animations. These can be found in the "Portfolio" page. Two of the portfolio items are animations and the other two transform when you hover over them.
I made the images responsive by using max-width: 100% and the responsive aspect can be seen very clearly when resizing with the image that I used in my header for my logo.