.arrow {
  width: 0; 
  height: 0; 
}

.arrow--up {
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  
  border-bottom: 5px solid white;
}

.arrow--down {
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  
  border-top: 5px solid white;
}

.arrow--right {
  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent;
  
  border-left: 5px solid white;
}

.arrow--left {
  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent; 
  
  border-right: 5px solid white; 
}