Version 2.14+ will check for and include custom.css in /css. Custom CSS should be placed in this file, and is not overwritten during an upgrade.
Version 2.19+ will check for and include default.css in /css for applying custom CSS to default/login page.
Version 2.19 introduced theme support. Themes are located in /css of the web panel. The filename is expected to be xxxxxxx.bs.min.css. Where xxxx is the name of theme. If you'd like to create a custom theme, copy an existing theme and rename the file. Make your updates to the newly created file. If you would like to force or set a default theme in the panel it can be done so from the Settings Menu--> Panel Customization page.
These other files can be edited with the 'Panel Customization' tool in the settings menu.
- App_Data/Menu.inc: The menu template for the panel. Not overwritten during upgrade.
- The header.inc file is HTML and is shown above the login boxes on the login screen. Overwritten during upgrades.
- The footer.inc file is an HTML file that provides the HTML for the footer. Overwritten during upgrades.
- The login.txt file will display it's HTML contents below the login box on the login page. Not overwritten during an upgrade.