/* 樱花飘落效果：动态生成花瓣，CSS 动画飘落+左右摇摆+旋转 */
(function () {
  if (document.getElementById('sakura-container')) return

  // 容器：铺满全屏、不拦截鼠标事件
  var container = document.createElement('div')
  container.id = 'sakura-container'
  container.style.cssText =
    'position:fixed;top:0;left:0;width:100%;height:100%;' +
    'pointer-events:none;z-index:9999;overflow:hidden;'
  document.body.appendChild(container)

  // 样式与飘落关键帧（S 形摆动 + 旋转）
  var style = document.createElement('style')
  style.textContent =
    '.sakura-petal{' +
    '  position:absolute;top:-12%;' +
    '  background:#ffb7c5;border-radius:100% 0 100% 0;' +
    '  opacity:.85;will-change:transform;' +
    '  animation:sakura-fall linear infinite;' +
    '}' +
    '@keyframes sakura-fall{' +
    '  0%{transform:translate(0,-12vh) rotate(0deg);}' +
    '  25%{transform:translate(18px,25vh) rotate(90deg);}' +
    '  50%{transform:translate(-18px,50vh) rotate(180deg);}' +
    '  75%{transform:translate(18px,75vh) rotate(270deg);}' +
    '  100%{transform:translate(0,112vh) rotate(360deg);}' +
    '}'
  document.head.appendChild(style)

  var PETALS = 28
  for (var i = 0; i < PETALS; i++) {
    var p = document.createElement('div')
    p.className = 'sakura-petal'
    var size = 8 + Math.random() * 10 // 8~18px
    p.style.width = size + 'px'
    p.style.height = size + 'px'
    p.style.left = Math.random() * 100 + 'vw'
    p.style.background = Math.random() > 0.5 ? '#ffb7c5' : '#ffc8d6'
    p.style.animationDuration = (6 + Math.random() * 6).toFixed(2) + 's' // 6~12s
    p.style.animationDelay = (-Math.random() * 12).toFixed(2) + 's' // 错落起步
    container.appendChild(p)
  }
})()
