BBlocks are self contained structural elements in Gantry 5 that can be particles, positions or spacers. They have several controls, such as sizing, but also allow you to select from a dropdown list of variations, as well as insert your own CSS classes.
A collection of additional variations for structural and subtle stylistic adjustments.
Effects and classes should be applied to the block within the Layout Manager, rather than in the module parameters, to ensure the desired effect is achieved.