Twitter and Medium co-founder Biz Stone joined audiovisual entertainment startup Chroma's board of directors.  The company aims to tap into his design, product development, and brand-building expertise. Stone was previously an angel investor in Chroma.  More: Chroma was founded in 2021 by Andreas Pihlström, who also leads the firm as its CEO.  Pihlström had previously led the design and prototyping at Pinterest, Beats Music, and VSCO.  Stone outlined that the firm must narrow its scope considering the small team size.  Stone expects to hold several meetings with the startup every month.  Chroma previously raised €1.6M ($1.7M) in pre-seed funding, followed by €5.1M ($5.4M) in seed funding from VCs Singular and Adjacent.  The firm is backed by Pinterest co-founders Evan Sharp and Ben Silbermann and Berlin's angel syndicate SpotiAngels.