Header not working

I tried to import your json file & it works fine. Then the issue lies with the import on your site.

Did you have any security plugin installed? If yes, try to disable & import it again & see if it works.

If not, then most likely it's your server firewall stripped off the <style> & <script> tag during the import.

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For these 2 sites:
https://careers.mainroad.ca/
https://careers.mainroadgrostg.wpengine.com/

Are they on the same hosting? If same hosting, then if the import works on one side, it should work on the other one as well, unless there's some Wordpress plugin causing the conflict. You may try to enable Safe Mode & see if you can import it correctly: WP Admin > Divi > Support Center > Safe Mode > Enabled

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If it's not a plugin issue, then it's should be your server firewall issue. If your host can't help with that, then you will need to go to each code module & insert the missing <style> & <script> tag.

----------

<style> tag is to wrap CSS code.

For example:
<style>
.et_pb_sticky_placeholder {
pointer-events: none!important;
}
#page-container .free-header-menu .et-menu {
margin: 0!important;
padding: 0!important;
}
</style>

-----------

<script> tag is to wrap jQuery code.

For example:
<script>
jQuery(function($){
xxxxxx
});
</script>