2017 redesign

[pkra]

Resolves #76

[pkra]

• use siteURL in nav instead of hardcoded links
• partners: add padding to links
• card card--popout: add padding-bottom
• Typos:
  • MathJax-User (should be "Users")
  • SIAMf (trailing f)

[pkra]

pushed final fixes.

[pkra]

one more fix and waiting for final feedback after the SC meeting.