* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  outline: 0;
}
body {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: #191919;
  position: relative;
}

#slider {
  width: 100%;
  height: 100vh;
  max-height: 100%;
  position: relative;
}
#slider img {
  opacity: 0;
  position: absolute;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: opacity 0.6s linear;
}
#slider img.selected {
  opacity: 1;
}

.controls {
  position: absolute;
  background: rgba(0, 0, 0, 0.3);
  bottom: 0px;
  width: 100%;
  height: 30px;
  padding: 40px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.controls button {
  display: block;
  border: 1px solid rgb(185, 185, 185);
  background: transparent;
  background-size: 200%;
  padding: 10px 30px;
  min-width: 110px;
  color: rgb(185, 185, 185);
  font-weight: bold;
  text-transform: uppercase;
  font-size: 12px;
  letter-spacing: 1px;
  cursor: pointer;
  transition: 0.2s all linear;
  -webkit-tap-highlight-color: transparent;
}
.controls button:hover {
  color: #fff;
  border-color: #fff;
}

@media (max-width: 600px) {
  .controls button {
    font-size: 10px;
    width: 70px;
  }
  .controls {
    padding: 50px 10px;
  }
}