/* ===================== BASE STYLES ===================== */
body {
  font-family: "Segoe UI", Roboto, sans-serif;
  background: #e0e4eb;
  color: #333;
  margin: 0;
  padding: 40px;
}

h1 {
  text-align: center;
  margin-bottom: 50px;
  font-size: 36px;
  font-weight: 700;
  color: #1f1f1f;
  display: inline-block;
  position: relative;
  padding-bottom: 10px;
}

h1::after {
  content: '';
  display: block;
  width: 60%;
  height: 6px;
  margin: 8px auto 0;
  border-radius: 4px;
  background: linear-gradient(90deg, #ff9a9e, #fad0c4, #a18cd1);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

/* ===================== TREE CARDS ===================== */
.tree {
  max-width: 900px;
  margin: 0 auto;
}

.card {
  background: #fff;
  border-radius: 12px;
  padding: 16px 20px;
  margin-bottom: 8px;
  border: 1px solid #d3d7de;
  box-shadow: 0 5px 15px rgba(0,0,0,0.07);
  cursor: pointer;
  position: relative;
  transition: all 0.25s ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}

.card .title {
  font-weight: 600;
  font-size: 18px;
  color: #1f1f1f;
  margin-bottom: 6px;
  border-left: 4px solid #a18cd1;
  padding-left: 8px;
}

.card .description {
  font-size: 14px;
  color: #555;
  margin-top: 4px;
}

.children {
  margin-top: 10px;
  margin-left: 20px;
  border-left: 3px solid #ccc;
  display: none;
  transition: all 0.3s ease;
}

.example {
  background: #f9fafc;
  padding: 8px 12px;
  border-radius: 8px;
  margin-top: 6px;
  font-size: 14px;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.2s ease;
}

.example:hover {
  background: #f1f3f8;
  transform: translateX(2px);
}

.memo {
  background: #ffeeba;
  padding: 8px 12px;
  border-radius: 8px;
  margin-top: 4px;
  font-size: 13px;
  color: #856404;
  border: 1px solid #ffd966;
  cursor: default;
  font-style: italic;
  line-height: 1.4em;
}