I am troubleshooting a development site and the contribution pages working under Civicrm 4.6.30 and Joomla 3.6.5 are not working under joomla 3.8 and Civi 4.7.23. Formatting of form is screwed up (alignment, form field lengths, etc.) are incorrect and most importantly, the total amount for selected options are not totaling. I have tried reinstalling Civi 4.7.23 and experimenting with changes to civicrm.css, but nothing works. I saw a post suggesting clearing civi caches and logs, which I have done, but still no go. URL is form url. Any ideas would help. Thanks, K.
CiviCRM is not yet compatible with Joomla 3.8. See here. As you will see, there is a patch. The patch resolved all the issues I was aware of, but is not yet approved.