/* ================= GLOBAL ================= */

body {
  font-family: Arial, sans-serif;
  background: #f5f7fa;
  margin: 0;                 /* changed from padding */
}

/* ================= TABS ================= */

#tabs {
  display: flex;
  padding: 10px 20px;
  background: #f2f2f2;
  border-bottom: 1px solid #ccc;
}

.tab {
  margin-right: 8px;
  padding: 8px 14px;
  text-decoration: none;
  color: black;
  background: #ddd;
  border: 1px solid transparent;
  border-radius: 4px;
}

.tab:hover {
  background: #ccc;
}

.tab.active {
  background: white;
  border: 2px solid #333;
  font-weight: bold;
}

/* ================= PAGE CONTENT ================= */

#content {
  padding: 20px;
}

h1 {
  text-align: center;
}

/* ================= TREE CONTAINER ================= */

#tree-container {
  margin-top: 40px;
  overflow-x: auto;
}

/* ================= TREE LAYOUT ================= */

.tree-node {
  display: inline-block;
  text-align: center;
  margin: 0 20px;
  position: relative;
}

/* Node box */
.node-box {
  background: #ffffff;
  border: 2px solid #4a90e2;
  border-radius: 6px;
  padding: 10px 14px;
  cursor: pointer;
  min-width: 180px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.15);
}

.node-box:hover {
  background: #eaf2ff;
}

/* Children container */
.children {
  display: flex;
  justify-content: center;
  margin-top: 40px;
  position: relative;
}

/* vertical line from parent */
.children::before {
  content: "";
  position: absolute;
  top: -20px;
  left: 50%;
  width: 2px;
  height: 20px;
  background: #4a90e2;
}

/* horizontal line connecting children */
.children::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: #4a90e2;
}