Looks like you set your settings back and the page is loading again from the “www.art” subdomains again. After some further checking there appears to be a redirect happening at your origin that is adding the WWW back even after you changed your A record. Which is causing the problem. Since you are using WordPress that could be a settings change in the ADMIN area. Otherwise, there is a redirect occurring at the server (before we are involved).
Long story short, if you want your site accessible via SSL at art. you will need to disable the redirect at your origin adding www. Once that is disabled you would want to have the A record of art. without www included.
If you want to have the two level subdomain with www and art you would need to add-on the Dedicated SSL with Custom Hostnames feature ($10/month) to get the SSL working with the two level subdomain.
If this still isn’t making sense, please submit a support ticket and share the ticket number with me. We might need to get into more detail than is ok in a public forum.