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HTML

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CSS

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CSS Base

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JavaScript

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JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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HTML 

              
                <!-- Toggle layout-overflow class to turn on overflow panels -->
<div class="layout-cell layout-scrollbar">
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
  <div class="component">Component</div>
</div>
!

CSS 

              
                /* Variables */
:root {
  --scrollbar-size: .375rem;
  --scrollbar-minlength: 1.5rem; /* Minimum length of scrollbar thumb (width of horizontal, height of vertical) */
  --scrollbar-ff-width: thin; /* FF-only accepts auto, thin, none */
  --scrollbar-track-color: transparent;
  --scrollbar-color: rgba(0,0,0,.2);
  --scrollbar-color-hover: rgba(0,0,0,.3);
  --scrollbar-color-active: rgb(0,0,0);
}

/* Use .layout-scrollbar-obtrusive to only use overflow if scrollbars don’t overlay */
.scrollbar-test,
.layout-cell {
  overscroll-behavior: contain;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  -ms-overflow-style: -ms-autohiding-scrollbar;
  scrollbar-width: var(--scrollbar-ff-width);
}

/* This class controls what elements have the new fancy scrollbar CSS */
.layout-scrollbar {
  scrollbar-color: var(--scrollbar-color) var(--scrollbar-track-color);
}
/* Only apply height/width to ::-webkit-scrollbar if is obtrusive */
.layout-scrollbar-obtrusive .layout-scrollbar::-webkit-scrollbar {
  height: var(--scrollbar-size);
  width: var(--scrollbar-size);
}
.layout-scrollbar::-webkit-scrollbar-track {
  background-color: var(--scrollbar-track-color);
}
.layout-scrollbar::-webkit-scrollbar-thumb {
  background-color: var(--scrollbar-color);
  border-radius: 3px;
}
.layout-scrollbar::-webkit-scrollbar-thumb:hover {
  background-color: var(--scrollbar-color-hover);
}
.layout-scrollbar::-webkit-scrollbar-thumb:active {
  background-color: var(--scrollbar-color-active);
}
.scrollbar-test::-webkit-scrollbar-thumb:vertical,
.layout-scrollbar::-webkit-scrollbar-thumb:vertical {
  min-height: var(--scrollbar-minlength);
}
.scrollbar-test::-webkit-scrollbar-thumb:horizontal,
.layout-scrollbar::-webkit-scrollbar-thumb:horizontal {
  min-width: var(--scrollbar-minlength);
}


/* Demo Styles */
html,
body {
  min-height: 100%;
  margin: 0;
}
.layout-cell {
  padding: 1em;
  max-height: 50vh;
  margin: 5vw;
  border: 2px solid rgba(0,0,0,.1);
  background-color: #f9f9f9;
}
.component {
  font-family: sans-serif;
  text-align: center;
  outline: 1px dotted rgba(0,0,0,.2);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 15em;
}
.component:not(:first-child) {
  margin-top: 1em;
}
.component ~ .component:last-child {
  margin-bottom: 1em;
}
!

JS 

              
                /*
 * Scrollbar Width Test
 * Adds `layout-scrollbar-obtrusive` class to body if scrollbars use up screen real estate
 */
var parent = document.createElement("div");
parent.setAttribute("style", "width:30px;height:30px;");
parent.classList.add('scrollbar-test');

var child = document.createElement("div");
child.setAttribute("style", "width:100%;height:40px");
parent.appendChild(child);
document.body.appendChild(parent);

// Measure the child element, if it is not
// 30px wide the scrollbars are obtrusive.
var scrollbarWidth = 30 - parent.firstChild.clientWidth;
if(scrollbarWidth) {
  document.body.classList.add("layout-scrollbar-obtrusive");
}

document.body.removeChild(parent);
!
999px

Console