If a style is defined in more than one of these files, the JSP engine uses the definition in the last file that contains the style. Thus the settings you specify in the customization web pages override any other CSS files.
allstyles.css contains additional style definitions for the Actuate Java Component application. Modify allstyles.css to change any style definitions that are not handled within the customization web pages or the <context root>\iportal\activePortal\private\skins\<skinname>\css\skinstyles.css file. Changes to a style in allstyles.css affects all Java Component skins except the parameters page unless the customization web pages or a skin’s skinstyles.css file override it. To customize the parameter component, modify the style definitions in the <context root>\css\parameter.css file.