The phrase "crisp lines" refers to sharp and defined edges or boundaries. It indicates that something is very neat, clear, and distinct. Full definition
Modern design and decor combine the clean, crisp lines of stone, wood, cement, and bamboo into a fusion of European chic and tropical celebration. (stayintamarindo.com)
I it so difficult to get perfectly clean painted stripes with crisp lines and no bleeding this is a much much easier alternative. (ourcraftymom.com)
Many of her early paintings consisted of shapes that were more or less rectangular, often in silver, gray and black, defined by crisp lines and edges. (latimes.com)