body {
  font-family: Arial, sans-serif;
  margin: 0;
  background: #f2f2f2;
}

header {
  background-color: #900000;
  color: white;
  padding: 20px;
  text-align: center;
}

main {
  padding: 20px;
}

#tree {
  width: 100%;
  height: 600px;
  margin-bottom: 30px;
  background: white;
  border: 1px solid #ccc;
  border-radius: 8px;
}

form#form-tambah {
  background: #fff;
  padding: 20px;
  max-width: 400px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

form#form-tambah h2 {
  margin-top: 0;
}

form#form-tambah input, form#form-tambah button {
  width: 100%;
  padding: 10px;
  margin-top: 10px;
  box-sizing: border-box;
}

form#form-tambah button {
  background-color: #900000;
  color: white;
  border: none;
  cursor: pointer;
  transition: background 0.3s;
}

form#form-tambah button:hover {
  background-color: #b00000;
}

.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  display: none;
  justify-content: center;
  align-items: center;
}

.modal-content {
  background: white;
  padding: 20px;
  max-width: 400px;
  border-radius: 8px;
  position: relative;
}

.close-button {
  position: absolute;
  top: 10px;
  right: 14px;
  font-size: 20px;
  cursor: pointer;
}