效果图：
代码：
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><style>html,body {margin: 0;padding: 0;}#allmap {position: absolute;width: 100%;height: 100%;z-index: -1;top: 0;left: 0;}.box {bac
