Hotclutch

The warnings are related to the use of structured data which is hard coded into the product_listing.php module file.

Looks like all IPs in that range are located in Singapore, so no. https://cleantalk.org/blacklists/as136907/159.138.0.0/16

First try blocking with robots.txt User-agent: Facebot Disallow: /

Sorry it's not clear what you're trying to do. a link to your site so that we can see what you're trying to do ?

you can also try replacing href="#" with href="javascript:void(0)", or remove the href all together.

If you specify href="#" then that is where you will go when clicked. You need to put the correct URL into href.

Your server is most likely on php 7. Your shop version is anything up to the last official version of osCommerce, which is not php 7 compliant.

may as well delete the OP also if it's not allowed to talk about Opencart ...

You answered your own question here, and that's all you need to do. Apart from that you need to make sure that user.css is then called after the bootstrap css.

It's down to 13K if this information is to be believed. https://www.ecommerceceo.com/open-source-ecommerce/

user.css should be loaded after the bootstrap css to achieve what you asked in the first post is a simple matter of putting <h1 class="h6">Heading Here</h1>

It's your project, you can change whatever file you like, no one should be advocating any different. That might be a vision, but the CE is far from that stage ,and i doubt it ever will be. Last time i checked there was code being added to the template files even.

you can change the font size in stylesheet.css in admin/includes/

you can do it in both configure files. Then search the forum for the htaccess code to put down, which will force your non https version of the site to https. At the moment it's accessible via both.