Shower is great but building from HTML is too trivial. Jekyller hadn't been updated since March, leaving, as @kizu said,

a lot of things to refactor

With these commits, we have a completely-reviewed-and-refactored Jekyller. Here is a done list:

• Update all the submodules, namely shower/core, shower/ribbon and shower/bright
• Update _config.yml to catch up Jekyll's changement (also fix issue Using absolute path for themes and shower, fixes #31 #32)
• Add .slide automatically for all sections in layout, leave others to be added manually in markdown (fix Merging classes #34 and Find out the best way to make “shouts” #8)
• Implement figcaptions in the way metioned by @pepelsbey (fix Markup for figure with captions #16)
• No syntax for <mark>, but to highlight codes by pygments (related to Syntax for <mark> tag #14)
• Use collections to manage all examples and slides (fix Create example pages #7), and create a index page of them (fix Create nice index page  #5).

I kept all the docs unchanged and look forward to your suggestions.