Create a visually striking and modern website banner image. The design should be clean but detailed, featuring a harmonious blend of minimalism and intricacy. Depict a sleek, contemporary cityscape with tall, futuristic buildings and clean lines, set against a backdrop of a twilight sky with soft gradients of blue and purple. Integrate subtle, detailed elements like floating airships, digital holograms, and glowing light trails weaving through the city. Include a serene river reflecting the city lights and a few trees or green spaces to add a touch of nature. The overall composition should be balanced, with an emphasis on modernity and sophistication, using a refined color palette of cool tones and crisp whites. Ensure the design is detailed enough to captivate viewers while maintaining a clean, uncluttered aesthetic --ar 7:4