Hilary, I have not downloaded the design file but code can be added in a couple of fashions:
  1. Web Properties > Website > HTML Code (head) <-- this for CSS scripts with <style> Tags. All appears just before the </head> Tag.
  2. Web Properties > Website > HTML Code (body) <-- usually JavaScript code with <script> Tags. All appears just before the </body> Tag.
  3. Web Properties > Page > HTML code (head) <-- this for CSS scripts with <style> Tags. My bet it the responsive IFRAME styling is here. All appears just before the </head> Tag.
  4. Web Properties > Page > HTML code (body) <-- usually JavaScript code with <script> Tags. All appears just before the </body> Tag.
  5. Web Properties > Placeholder > HTML code (head) <-- probably this one for CSS scripts with <style> Tags. All appears just before the </head> Tag.
  6. Web Properties > Website > HTML Code (body) <-- usually JavaScript code with <script> Tags and used for positioning of HTML content. Replaces the Placeholder with a DIV Tag wrapper and then your code/content, making it hierarchically sensitive.

Acorn