* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: #111;
}

.slider {
  position: relative;
  width: 800px;
  height: 400px;
  overflow: hidden;
  border-radius: 10px;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
}

.slides {
  width: 100%;
  height: 100%;
  display: flex;
}

.slide {
  min-width: 100%;
  transition: opacity 1s ease;
  display: none;
}

.slide.active {
  display: block;
}

button.prev,
button.next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background-color: rgba(0,0,0,0.5);
  color: white;
  border: none;
  padding: 10px 15px;
  cursor: pointer;
  border-radius: 50%;
  font-size: 20px;
  user-select: none;
}

button.prev:hover,
button.next:hover {
  background-color: rgba(255,255,255,0.3);
}

button.prev { left: 10px; }
button.next { right: 10px; }