What is the fine-grained topic of the following text: And if this has got your autumnal colour fingers excited, then how about introducing a fourth colour into the equation, such as a terracotta red (accentuated here with the vibrant pattern of my thistle cushion from my velvet Mairi Helena cushion collection). Only return the topic.
Introducing a fourth colour (terracotta red) into autumnal color scheme using a patterned cushion from the velvet Mairi Helena cushion collection.