I found the issue while looking at your theme. The theme author didn’t include all of the “header” code in the header.php file, they opted to create a file in their include folder called “top.php” which contains the code that generates the top portion of their theme.
So how do we fix this? The easiest way is to go to the Car Demon folder and then go to the “theme-files” sub-folder and copy the “archive-cars_for_sale.php”, “search.php”, and “single-cars_for_sale.php” files and put them in the root of your theme directory.
In each one of these files you’ll need to make a small change.
Right below the segment where it says;
get_header();
add this line;
include (THEME_INCLUDES . '/top.php');
upload the files and then go to the admin area “Cars for Sale” and select the sub-menu “Car Demon Settings”.
Once there you’ll see an option that says “Use included Theme Files”, set this to “No” and save your settings.
I believe this will resolve the majority of your issue. We may need to change a couple file paths and do some touch up work, but I think this will take care of the majority of issues.