This property allows specifying a global CSS class (indicated by an external CSS style sheet) to apply to a text. A CSS class (Cascading Style Sheet) is a format pattern that determines font type and size, paragraph alignment and spacing, among other features. By using CSS, users can apply a pre-defined format pattern to a text, unifying and speeding up text presentation. To apply a specific style, users can use the Style property. Default value of this property is the Normal style.