FieldLayout.setLabelCellClass

Sets one or more CSS classes to be applied to label table cells when displaying a Field Control, or applied to the table cells containing other control types. Multiple classes are specified by using a space between the class names, as per the HTML class parameter.

These classes are configured in the designer using the Advanced Properties button within the layout properties Styling Assistant.

Further documentation.

Parameters

java.lang.String  labelCellClass,