updated epa styles.css file

[dannypeterson]

Updated the epa css file to comply with EPA standards and procedures found here. Main changes:

• updating the EPA header colors
• removing transition when hovering over header links to comply with updated EPA site
• overwriting transitions applied to every element in epa-hawc.css
• Updated docs to explain updating future epa styles
  

[shapiromatron]

Hi @dannypeterson, sorry I totally missed one important thing. We'll want to make no edits at all to this file so we can just drop it in; and then make edits to static/css/epa-hawc.css. That file gets loaded after and can update as needed; Pinging @caseyhans ; he can help translate these revisions if needed.

[shapiromatron]

ok to merge @caseyhans ? I'm fixing links in the footer.

[shapiromatron]

Looks good, but I had to make three changes:

• 8bfe6bf fix usa-banner caret
• d1c7c74 update header search button and main menu when collapsed
• e0d4dde update footer links

I compared the header/footer to epa.gov and found that that there were a number of differences. Hopefully the are explained well in the commits above.

@caseyhans - requesting your review please; ok to merge from my end.
@dannypeterson - fyi - had to make some additional edits b/c the header/footer looked pretty different. Let me know if you'd like me to walk you through the edits tomorrow.