* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: -apple-system, BlinkMacSystemFont, Roboto, Helvetica, sans-serif
}

html, body {
  height: 100%;
  background: #fff;
}

body {
  display: flex;
  flex-direction: column;
}

#background {
  flex: 1 0 auto;
  background-image: url('background-500.jpg');
  background-size: cover;
  background-position: top center;

  @media (min-width: 500px) {
    background-image: url('background-1024.jpg');;
  }

  @media (min-width: 1024px) {
    background-image: url('background-1920.jpg');;
  }

  @media (min-width: 1920px) {
    background-image: url('background-4808.jpg');;
  }
}

main {
  padding: 1rem;

  header {
    margin-bottom: 1rem;

    h1 {
      font-size: 2rem;
      color: #000;
      text-align: center;
      margin-bottom: .5rem;
    }

    p {
      font-size: 1.2rem;
      text-align: center;
    }
  }

  nav {
    display: flex;
    flex-direction: column;

    a {
      display: flex;
      justify-content: center;
      align-items: center;
      text-decoration: none;
      color: #000;
      font-size: 2rem;
      border-top: 1px solid #ccc;
      padding: .5rem 0;

      .app-icon {
        width: 2.5rem;
        margin-right: 1rem;
      }

      .link-symbol {
        margin-left: .25rem;
      }
    }
  }
}

@media (min-width: 31.25rem) {
  main {
    padding: 2rem;
    position: fixed;
    bottom: 5%;
    left: 50%;
    translate: -50% 0;
    width: 30rem;
    border-radius: 0.5rem;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(4px);
  }
}