Complex sentence: She and her husband made their reputation with silver in the then-popular Rococo style from France; however, by the time of her partnership with Cowles, tastes had shifted towards Neoclassicism, and the company changed its output accordingly.
Split into simpler sentences: She and her husband made their reputation with silver in the then-popular Rococo style from France. However, by the time of her partnership with Cowles, tastes had shifted towards Neoclassicism, and the company changed its output accordingly.