#carousel {
  max-width: 600px;
  margin: auto;
  position: relative;
}
.carousel-prev, .carousel-next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: #fff;
  border: none;
  font-size: 2rem;
  cursor: pointer;
  z-index: 2;
  padding: 0.5em 1em;
  border-radius: 50%;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}
.carousel-prev { left: 10px; }
.carousel-next { right: 10px; }

@media (max-width: 600px) {
  #carousel {
    max-width: 100vw;
  }
  .carousel-prev, .carousel-next {
    font-size: 1.5rem;
    padding: 0.3em 0.7em;
  }
}