* {
    box-sizing: border-box;
}
html {
    font-family: sans-serif;
    scroll-snap-type: mandatory;
    scroll-snap-points-y: repeat(100vh);
    scroll-snap-type: y mandatory;
}
section {
    border-bottom: 1px solid white;
    padding: 1rem;
    height: 100vh;
    scroll-snap-align: start;
    text-align: center;
    position: relative;
}
h1  {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    text-align: center;
    color: black;
    width: 100%;
    left: 0;
    font-size: calc(1rem + 3vw);
}

#section_two {
  background-color: blue;
}

.blue {
  position: fixed;
  width: 75%;
  color: white;
  line-height: 100px;
  text-align: center;
  z-index: 1;
  bottom: 5%;
  left: 12.5%;
  background: #282828;

  &:not(:last-of-type) {
    margin-bottom: 5px;
  }

  iframe {
    display: block;
    transition: opacity 0.125s;
    .js & {
      opacity: 0;

      &.loaded {
        opacity: 1;
      }
    }
  }
}