From Joomla! Documentation
Note that this example includes class additions because the examples are taken using mod_mainmenu. The suffix "_menu" to the div class and the "menu" class on the ul tag are not present with other modules.
Note that the Module chrome doesn't necessarily change the appearance all that much - this depends on the CSS used in the template. For example, the 'none' and 'horz' chromes look very similar, although the underlying HTML code is very different.
另外要注意：The horz is just the table layout, wrapped in a table, tr, and td.
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/.