* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
:root {
  font-family: Arial, Helvetica, sans-serif;
}
ul {
  list-style: none;
}
a {
  text-decoration: none;
  color: black;
}

.container {
  margin: 20px auto;
  width: 830px;
  padding-left: 15px;
  padding-right: 15px;
  @media (max-width: 830px) {
    width: 100%;
  }
  .image {
    position: relative;
    .slide-number {
      position: absolute;
      left: 10px;
      top: 10px;
      color: white;
      background-color: rgba(0, 0, 0, 0.8);
      padding: 5px 10px;
      border-radius: 5px;
      font-size: 18px;
      z-index: 2;
      @media (max-width: 500px) {
        font-size: 12px;
      }
    }
    ul {
      position: relative;
      li {
        img {
          transition: opacity 1s;
          position: relative;
          max-width: 100%;
          &.active {
            z-index: 1;
          }
          &:not(.active) {
            opacity: 0;
            position: absolute;
            top: 0;
            left: 0;
          }
        }
      }
    }
  }
  .navigation {
    margin-top: 10px;
    position: relative;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 10px;
    user-select: none;
    @media (max-width: 500px) {
      flex-direction: column;
    }
    button {
      background-color: #009688;
      color: white;
      padding: 5px 0;
      width: 150px;
      border: none;
      outline: none;
      cursor: pointer;
      border-radius: 5px;
      font-size: 16px;
      transition-duration: 1s;
      transition-property: background-color color;
      &.inactive {
        background-color: rgba(0, 150, 136, 0.5);
        pointer-events: none;
      }
    }
    ul {
      display: flex;
      gap: 5px;
      a {
        display: block;
        background-color: #f6f6f6;
        font-weight: bold;
        font-size: 18px;
        padding: 4px 10px;
        border-radius: 5px;
        cursor: pointer;
        transition-duration: 1s;
        transition-property: background-color color;
        &.active {
          background-color: #009688;
          color: white;
        }
      }
    }
  }
}