Thanks for asking.
I checked your website and can confirm that media attachment page is not inheriting the rest of website layout, especially header. Please confirm following:
- Please make sure that header you have created is global header so that media attachment page inherit the global header. Here's a screencast on how to set global header.
- If you have header set as Global then issue might be with the version of Pro Theme you are using. I see that you are using old version of Pro Theme 2.0.4. Please update Pro to the most recent release 2.2.5 to avoid any compatibility issues.
Theme Update guide: Please take a look at following article to update Pro Theme.
Let us know how it goes.