I was trying to integrate eStore plugin with Customizr theme and ran into a problem that the credit card input page was displaying "mixed content" rather than 100% https / ssl encrypted data. I needed ssl because I will not redirect the user to an external gateway (I'll use PayPal Pro or Authorize.net AIM). I isolated the problem as the header logo which was being delivered by http, not https. I believe the issue arises in 'class-main-header.php' in '<wp dir>/wp-content/themes/customizr/parts/'. The line
$logo_src = esc_url ( tc__f ( '__get_option' , 'tc_logo_upload' )) ;
was resolving to http, not https. I don't know the root cause but I did hard code
$logo_src = "https://www.<mysite>.com/<wp dir>/wp-content/uploads/2013/07/<mylogo>.gif" ;
which resolved the problem. Hope this helps others who may be having a similar issue.