.filtrar-tribos {
  border: 1px solid #ddd;
  border-radius: 4px;
  margin: 10px 0;
  padding: 8px 12px;
  width: auto;
  min-width: 160px;
  font-size: 14px;
  box-sizing: border-box;
}

.filtrar-tribos:focus {
  outline: none;
  border-color: #4a90e2;
}