English to Chinese Marketing Textiles / Clothing / Fashion

阿玛尼包的产品描述：
Different manifacturings recall the history of the ‘maison’, reinterpreting archive pieces with a fresh and actual touch, as for the soutage, where the accurate realization of small fabric mignon have always been part of our DNA.An important ‘fil rouge’ beetween the different families is given by the metal details and also by the material used, more classic like the palmellato or more seasonal like the animalier ones.

fil rouge 是什么意思？