I'm playing around with Chris Coyiers brilliant approach to

Windows screenshot with the unwanted gap:

CodePudding user response：

The problem is from the reserved width for the y-scroller, and you only hide the x-scroller by overflow-x: hidden; on body.

You can add this to your styles that will help you to get rid of the reserved width of the scroller on body.

body::-webkit-scrollbar {
  display: none;
}

Full code

var viewportHeader = document.querySelector(".viewport-header");

document.body.addEventListener("scroll", function(event) {
  var opacity = (document.body.offsetHeight - document.body.scrollTop) / document.body.offsetHeight;
  var scale = (document.body.offsetHeight - document.body.scrollTop) / document.body.offsetHeight;
  document.documentElement.style.setProperty('--headerOpacity', opacity);
  document.documentElement.style.setProperty('--headerScale', scale);
});

:root {
  --headerOpacity: 1;
  --headerScale: 1;
}

.video-header {
  position: absolute;
  text-align: center;
  width: 100vw;
  height: 100vh;
}

.video-header,
.video-header video,
.video-header .viewport-header {
  width: 100vw;
  height: 100vh;
  position: absolute;
  top: 0;
  left: 0;
}

.video-header video {
  background: brown;
  object-fit: cover;
}

.video-header .viewport-header {
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 1;
  opacity: var(--headerOpacity);
  transform: scale(var(--headerScale));
}

html,
body {
  height: 100vh;
  overflow-x: hidden;
}

body::-webkit-scrollbar {
  display: none;
}

html {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  font-size: 150%;
  line-height: 1.4;
}

body {
  margin: 0;
}

h1 {
  font-family: "Syncopate", sans-serif;
  color: white;
  text-transform: uppercase;
  letter-spacing: 3vw;
  line-height: 1.2;
  font-size: 3vw;
  text-align: center;
}

h1 span {
  display: block;
  font-size: 10vw;
  letter-spacing: -1.3vw;
}

main {
  background: white;
  position: relative;
  padding: 1rem;
  margin-top: 100vh;
}

main::before {
  content: "";
  width: 100vw;
  height: 100vh;
  position: absolute;
  left: 0;
  top: -100vh;
}

main p {
  max-width: 600px;
  margin: 1rem auto;
}

<header >
  <video src="https://css-tricks-post-videos.s3.us-east-1.amazonaws.com/Island - 4141.mp4" autoplay loop playsinline muted></video>
  <div >
    <h1>
      Explore
      <span>Montana</span>
    </h1>
  </div>
</header>

<main>
  <p>
    test
  </p>
  <p>
    test
  </p>
  <p>
    test
  </p>
  <p>
    test
  </p>
  <p>
    test
  </p>
  <p>
    test
  </p>
</main>