The visible appearance and behavior of events is modified by editing the style attributes. The mechanism used to represent styles is borrowed from CSS (cascading style sheets) used by HTML for web pages. Although the syntax is similar, the elements properties are completely different.
Sets of attributes can be attached to categories and events. The attributes can be defined directly in each category and event or the attributes can be defined in a style list attached to the timeline file. Attributes can also be defined in external files with the .qss suffix and included by multiple timeline files.
A set of attributes is usually attached to a category or event by setting the selector for that set into the class field of that category or event. The definition of a selector in the styles section or in a QSS file should start with "." (period) when that selector is going to be used in the class column of a category or event.
The attributes are grouped into six sections: