"Design a futuristic floating house integrated prominently into a cascading waterfall. The house should have a round shape with an observatory for stargazing and feature a serene interior, blending modern minimalism with natural materials for a cozy atmosphere. Construct the exterior from elegant marble with golden rod window frames, incorporating vibrant, watery tones in shades of teal, aquamarine, and deep blue. The walls should have a textured ceramic finish in complementary bright colors. Ensure the house is the focal point, partially submerged in the water, with the waterfall cascading around it. Surround the scene with lush greenery and koi fish swimming in the clear pools formed by the waterfall, enhancing the tranquil atmosphere. The overall design should promote relaxation and a deep connection to nature, all in 4K high resolution, highlighting the beauty and elegance of the materials."