That line of non-fluffy fabric about a quarter of the way from the edge of your bath towels has an odd name but also a rather ...

It is difficult to pinpoint when weavers first considered incorporating dobby borders on fabrics, but they started being a staple on bath towels sometime after the dobby loom came about in 1843 ...

In this case, that idiom refers to the fabrics used, cutting and sewing techniques, button selection, finishing techniques, cutting patterns, and almost every other step of the shirt-making process.