* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: white;
  color: #333;
  line-height: 1.6;
  padding: 20px;
}

.container {
  /* max-width: 800px; */
  /* margin: 0 auto; */
  background: white;
  /* padding: 40px; */
  border-radius: 8px;
  /* box-shadow: 0 2px 10px rgba(34, 34, 34, 0.05); */
}

header {
  text-align: center;
  margin-bottom: 0px;
  padding-bottom: 0px;
  /* border-bottom: 2px solid #eee; */
}

h1 {
  font-size: 20px;
  font-weight: 300;
  color: #222;
  margin-bottom: 8px;
  text-align: left;
  font-style: italic;
  font-weight: 600;
}

.subtitle {
  color: #666;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 2px;
}

.tree {
  margin-top: 20px;
}

.tree-item {
  margin-bottom: 4px;
}

.tree-node {
  display: flex;
  align-items: center;
  padding: 12px 16px 10px 0px;
  cursor: pointer;
  user-select: none;
  transition: background-color 0.2s;
  border-radius: 4px;
}

.tree-node:hover {
  background-color: #f5f5f5;
}

.tree-node.active {
  background-color: #f0f0f0;
}

.tree-toggle {
  font-size: 12px;
  color: #999;
  transition: transform 0.2s;
  margin-right: 10px;
  width: 16px;
  display: inline-block;
  text-align: center;
  transform: rotate(0deg);
}

.tree-icon {
  margin-right: 10px;
  font-size: 18px;
}

.tree-label {
  flex: 1;
  font-size: 15px;
  font-weight: 500;
  color: #333;
}

.tree-node:not(.collapsed) .tree-toggle {
  transform: rotate(90deg);
}

.tree-content {
  margin-left: 28px;
  border-left: 2px solid #e0e0e0;
  padding-left: 16px;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
}

.tree-content.expanded {
  max-height: 5000px;
  transition: max-height 0.5s ease-in;
}

.item-list {
  padding: 12px 0;
}

.item-link {
  display: block;
  padding: 4px 6px;
  margin-bottom: 4px;
  color: #555;
  text-decoration: none;
  border-radius: 4px;
  transition: all 0.2s;
  font-size: 14px;
}

.item-link:hover {
  background-color: #f8f8f8;
  color: #000;
  padding-left: 16px;
}

.item-link:visited {
  color: #888;
}

.item-title {
  font-weight: 500;
}

.item-meta {
  font-size: 12px;
  color: #999;
  margin-top: 4px;
}

.loading {
  text-align: center;
  padding: 20px;
  color: #999;
  font-size: 14px;
  display: none;
}

.loading.show {
  display: block;
}

.empty-state {
  padding: 20px;
  /* text-align: center; */
  color: #999;
  font-size: 14px;
}

@media (max-width: 600px) {
  .container {
    padding: 20px;
  }

  h1 {
    font-size: 24px;
  }

  .tree-content {
    margin-left: 16px;
  }
}