"Design a simple light, minimalist flat design banner background for an alternative asset investment platform centered on art and collectible marketplaces. Focus on simplicity with clean lines and soft gradients, creating an open, airy feel. Use light pastel tones like soft blues, warm golds, and pale pinks to give the design a modern, optimistic look. Incorporate simple flat icons of art pieces, rare collectibles, and subtle upward-trending graphs. The backdrop features a minimal city skyline with gentle gradient shading, evoking a sense of growth and opportunity without overcrowding the design. Keep the composition spacious, light, and visually refreshing."