@import url('https://fonts.googleapis.com/css2?family=Gluten:wght@100..900&display=swap');

html {
      box-sizing: border-box;
      background: #ffc600;
      font-family: 'Gluten', Arial;
      font-size: 20px;
      font-weight: 200;
    }

    body {
      margin: 0;
    }

    *, *:before, *:after {
      box-sizing: inherit;
    }

    .panels {
      min-height: 100vh;
      overflow: hidden;
      display: flex;
    }

    .panel {
      background: #6B0F9C;
      box-shadow: inset 0 0 0 5px rgba(255,255,255,0.1);
      color: white;
      text-align: center;
      align-items: center;
      /* Safari transitionend event.propertyName === flex */
      /* Chrome + FF transitionend event.propertyName === flex-grow */
      transition:
        font-size 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
        flex 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
        background 0.2s;
      font-size: 20px;
      background-size: cover;
      background-position: center;
      flex: 1;
      justify-content: center;
      align-items: center;
      display: flex;
      flex-direction: column;
    }

    .panel1 { background-image:url(img/beach.jpg); }
    .panel2 { background-image:url(img/country.jpg); }
    .panel3 { background-image:url(img/forest.jpg); }
    .panel4 { background-image:url(img/road.jpg); }
    .panel5 { background-image:url(img/shore.jpg); }

    /* Flex Items */
    .panel > * {
      margin: 0;
      width: 100%;
      transition: transform 0.5s;
      flex: 1 0 auto;
      display: flex;
      justify-content: center;
      align-items: center;
    }
    .panel > *:first-child {
      transform: translateY(-100%);
    }
    .panel.open-active > *:first-child {
      transform: translateY(0);
    }
    .panel > *:last-child {
      transform: translateY(100%);
    }
    .panel.open-active > *:last-child {
      transform: translateY(0);
    }
    .panel p {
      text-transform: uppercase;
      text-shadow: 0 0 4px rgba(0, 0, 0, 0.72), 0 0 14px rgba(0, 0, 0, 0.45);
      font-size: 2em;
    }

    .panel p:nth-child(2) {
      font-size: 4em;
    }

    .panel.open {
      flex: 5;
      font-size: 40px;
    }