Embedded PDF viewer

1. Using simple iframe
   • Debug: cannot display properly on ios (safari)
   • ios system render iframe pdf viewer as an image (of first page)
   • Solution: Google drive viewer
   • Other possible ways: Use pdf.js
2. Improvements
   • Add button to show pdf in gallery view
   • Sense mobile / desktop view (e.g. iframe/google drive viewer)

• [1986] Distinguishability of Conductivities by ECCT