html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  overflow-x: hidden;
  background: #f7f7f7;
  font-family: Arial, sans-serif;
  background-image: url('background.jpg'); /* 使用上传的背景图片 */
  background-size: cover; /* 确保背景覆盖整个页面 */
  background-position: center; /* 背景居中 */
  transition: background-position 0.5s ease-out; /* 动态效果 */
}

.page {
  min-height: 220vh; /* 确保足够的页面高度来支持滚动 */
}

.hero {
  position: relative;
  height: 100vh;
}

.structure-container {
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: rgba(247, 247, 247, 0.5); /* 半透明白色层，增强对比度 */
}

.black-box {
  width: 220px;
  height: 220px;
  background-color: #0e0e0e;
  box-shadow: 0 30px 60px rgba(0,0,0,0.35);
  border-radius: 4px;
  position: absolute;
  z-index: 10;
}

.transition-path {
  position: absolute;
  left: 50%;
  top: 0;
  width: 6px;
  height: 100%;
  background: #ececec;
  box-shadow: 0 0 12px rgba(0,0,0,0.06);
}

.aux-node {
  position: absolute;
  width: 14px;
  height: 14px;
  background: #101010;
}

.n1 { left: 22%; top: 65%; }
.n2 { left: 70%; top: 62%; }
.n3 { left: 78%; top: 38%; }

.logo {
  position: fixed;
  left: 20px;
  bottom: 20px;
  color: #111;
  z-index: 20;
}

.logo-mark { opacity: 0; }

.content {
  position: fixed;
  right: 6vw;
  bottom: 10vh;
  max-width: 420px;
  opacity: 0;
  visibility: hidden;
  color: #111;
}

.entry {
  min-height: 120vh;
  display: grid;
  place-content: center;
  gap: 16px;
}