Standard Module Chromes
From Joomla! Documentation
Note that this example includes class additions because the examples are taken using mod_mainmenu. The suffix "_menu" on the div class and the menu class on the unordered list (ul) tag are not present with other modules.
Note that the Module chrome doesn't change the appearance all that much—this depends on the CSS used in the template. For example, the none and horz chromes look similar, although the underlying HTML code is different.
Other notes: The horz is just the table layout, wrapped in a table, tr, and td.
Until Joomla! 3: The software controlling these is in the file /templates/system/html/modules.php.
Changes since Joomla! 4
- The standard chromes horz, rounded and xhtml have been removed from core.
- The core module chromes are controlled by JLayout files in directory /layouts/chromes/.