responsive: hide column header on smartphones
Shorten panel heading

before: 2014/5: Week 3 (May 11, 2014..May 17, 2014)
after: 2014/5: Week 3 (May 11..May 17)
Extract media queries for readability
Remove unneed DOM nesting to style easily
Cut comment by CSS
Reduce data attr, because it's dupe
Toggle-able comment and actions
Merge pull request #1 from sorah/responsive/expenses

Responsive/expenses