<head>
<style>
$finalHeight: 250px;
$finalWidth: 3 * $finalHeight;
$scrollBarHeight: 1px;

::-webkit-scrollbar {
  width: $scrollBarHeight;
  height: $scrollBarHeight;
}

::-webkit-scrollbar-button {
  width: $scrollBarHeight;
  height: $scrollBarHeight;
}

body {
  background: #111;
}

div {
  box-sizing: border-box;
}

.horizontal-scroll-wrapper {
  position: absolute;
  display: block;
  top: 0;
  left: 0;
  width: calc(#{$finalHeight} + #{$scrollBarHeight});
  max-height: $finalWidth;
  margin: 0;
  padding-top: $scrollBarHeight;
  background: #abc;
  overflow-y: auto;
  overflow-x: hidden;
  transform: rotate(-90deg) translateY(-$finalHeight);
  transform-origin: right top;
  & > div {
    display: block;
    padding: 5px;
    background: #cab;
    transform: rotate(90deg);
    transform-origin: right top;
  }
}

.squares {
  padding: $finalHeight 0 0 0;
  & > div {
    width: $finalHeight;
    height: $finalHeight;
    margin: 10px 0;
  }
}
</style>
</head>

<div class="horizontal-scroll-wrapper squares">
  <div>item 1</div>
  <div>item 2</div>
  <div>item 3</div>
  <div>item 4</div>
  <div>item 5</div>
  <div>item 6</div>
  <div>item 7</div>
  <div>item 8</div>
</div>