The brand is gaining market share in cosmetics, but a weak sales environment creates uncertainty heading into the next earnings report.Cosmetics retailer e.l.f. Beauty (ELF -0.29%) has been one of the fastest-growing consumer brands in recent years. The stock has tripled over the past three years following the company's rapid expansion in a growing cosmetics market. But 2024 has been challenging for many retailers, as stubbornly high inflation and other macroeconomic headwinds hurt consumer spending.Investo ...