PenciDesign Supporter replied
Staff Reply
Hi,
1. Please go to dashboard > Header Builder > Edit with the "Penci Header Builder" then add the HTML content to the mobile sidebar content like the screenshot below:

2. About the site loading issue, please go to Appearance → Customize → Speed Optimization → Optimize CSS: turn on the "Create Critical CSS" option. Clear all the caches and then check again.
Regards,
PenciDesign.