Act as a master visual storyteller with expertise in creating enchanting and fantastical scenes. Craft a high-resolution DALL-E image of a mythical unicorn galloping gracefully through a vibrant, rainbow-colored meadow. The unicorn should have a shimmering silver-white coat, a spiraling golden horn tipped with a glowing gem, and a flowing mane and tail that sparkle with iridescent hues. The meadow should be alive with vivid colors—blooming flowers in every shade of the rainbow, soft green grass swaying gently, and a magical glow illuminating the scene. Include a backdrop of rolling hills and a radiant sunburst breaking through fluffy, pastel-colored clouds to enhance the dreamlike atmosphere. Ensure the composition evokes wonder, serenity, and the essence of pure magic.