HTML5悬浮按钮设计教程

• +
• 或使用链接跳转功能：↑

.floating-btn {
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: 56px;
  height: 56px;
  background-color: #1E90FF;
  color: white;
  border: none;
  border-radius: 50%;
  box-shadow: 0 4px 8px rgba(0,0,0,0.3);
  font-size: 24px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
}

.floating-btn:hover {
  transform: scale(1.1);
  background-color: #104E8B;
  box-shadow: 0 6px 12px rgba(0,0,0,0.4);
}

window.addEventListener('scroll', function() {
  const btn = document.querySelector('.floating-btn');
  if (window.scrollY > 300) {
    btn.style.display = 'flex';
  } else {
    btn.style.display = 'none';
  }
});

• 设置合适的大小（至少 48x48px）便于手指点击
• 使用 position: fixed 保证始终可见
• 避免与其他固定元素重叠
• 考虑深色模式：用 prefers-color-scheme 做主题适配