app/views/spreadsheets/_d3_heatmap.html.erb use style tag in partial template

[nwoetzel]

a style tag is used in a partial template
http://www.w3schools.com/tags/tag_style.asp
This is not allowed or intended by any standard.
The rake test:functional also complains about this template
Probably finding another solution for that:
-full template, with proper head section
-globally defined styles with proper classes and selectors
might resolve that issue