Add light_gray variable to sass basics
Load assets list after viewframe
Add expand/collapse button to assetlist

Includes JS event handling. Surely there are better/more efficient ways of handling this. I’ll leave that to the experts. This illustrates what classes I need to change/add.
Style assetlist container and expand/collapse button

Note that expand/collapse button is animated via CSS3. Webkit-only for now, will work on cross-browser transitions later using compass instead of plain SASS.
Remove direct child selectors from assetlist child styles