A cute side-view underwater casual game start screen in a soft pastel 3D cartoon style, designed like a polished children's browser game interface. The scene shows a bright ocean floor with sun rays streaming down through clear blue water, floating bubbles, distant tiny fish silhouettes, and a dreamy coral reef environment filled with rounded pink, purple, blue, and mint corals, sea plants, shells, rocks, and sandy ground. Slightly left of center, a small mermaid puppy character inspired by a rescue-dog cartoon floats happily underwater, with a puppy face, big sparkling eyes, floppy ears, a tiny tiara-like head accessory, and a fish tail instead of hind legs, facing forward with a cheerful expression. On the right stands a whimsical candy-like coral lighthouse shaped like a pink-and-cream seashell tower with a glowing lantern room at the top, a pearl on the roof, circular shell windows, a small balcony, a purple door, and decorative coral details around the base. Overlay game UI elements directly on the scene: at top left, 2 rounded white pill buttons, the first reading "去灯塔" and the second showing "0/3"; at top right, 1 circular white pause button with a pause icon. Near the lighthouse, show 4 translucent colored target rings floating over interactive spots: 1 pink ring near the upper middle windows, 1 yellow ring near the upper right lantern area, 1 pale blue ring over a lower right shell window, and 1 large white-outlined ring around a purple jellyfish near the lower center-left. Add 3 collectible pearl-in-shell objects visible in the scene: 1 glowing golden pearl in an open shell near the center, 1 small dark blue pearl shell near the lighthouse base, and 1 red pearl shell resting on the bottom center UI panel. At the bottom center, place 3 rounded white control hint buttons with Chinese text: "方向键 / WASD", "空格 / 回车：放珠", and "Esc 回地图". Include a large semi-transparent rounded white panel behind the bottom controls. The overall image should feel joyful, safe, colorful, and magical, with high polish, gentle depth of field, soft lighting, glossy toy-like materials, and a kid-friendly mobile or web game aesthetic.
