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HTML

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Adding Classes

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About the <head>

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CSS

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CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

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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 

              
                <div class="wrapper">
	<div class="tabs">
		<div role="tablist" aria-label="FAQ">
			<button role="tab" aria-selected="true" id="what">What?</button>
			<button role="tab" aria-selected="false" id="when">When?</button>
			<button role="tab" aria-selected="false" id="how">How?</button>
		</div>
		<div role="tabpanel" aria-labelledby="what">
			<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Officia modi similique tenetur, itaque nam tempora, facilis porro vel nemo, illo eum inventore autem numquam cum delectus aperiam repudiandae! Porro delectus provident accusamus. Odit doloremque modi optio praesentium, saepe eius natus veniam inventore ipsam incidunt animi, iure, ex accusantium quis velit.</p>
			<p>Lorem ipsum dolor sit, amet consectetur adipisicing elit. Molestias eum blanditiis praesentium nemo magni. Soluta harum magnam perspiciatis numquam porro dignissimos, dicta atque aut eius quasi iure quidem nulla velit sapiente cupiditate ipsa, exercitationem recusandae repudiandae. Velit excepturi aliquam maiores.</p>
		</div>
		<div role="tabpanel" aria-labelledby="when" hidden>
			<p>Lorem, ipsum dolor sit amet consectetur adipisicing elit. Non, quam dolorum sit delectus molestias id consectetur perferendis ipsum voluptatum reiciendis, reprehenderit, iste quibusdam quisquam? Ad tempora cum quae, quisquam perferendis modi explicabo eligendi quis repellendus, vero non cumque eos autem!</p>
			<p>Lorem ipsum dolor sit amet consectetur, adipisicing elit. Deleniti exercitationem dolorum et blanditiis distinctio? A recusandae molestias repellat quo ipsum asperiores illo possimus voluptates suscipit saepe maxime fuga ea non corrupti voluptatum, rem accusantium fugiat nihil, ducimus modi aliquam est.</p>
		</div>
		<div role="tabpanel" aria-labelledby="how" hidden>
			<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Consequatur dignissimos fuga explicabo. Modi hic, minima odit nostrum cum illo, cupiditate, similique sequi delectus excepturi placeat non qui nemo sed facere adipisci. Quibusdam incidunt reprehenderit unde optio eligendi, voluptatem illum necessitatibus!</p>
			<p>Lorem, ipsum dolor sit amet consectetur adipisicing elit. Numquam dicta amet iusto ipsum sed enim impedit eius rem necessitatibus ad voluptate harum perspiciatis ut, perferendis ratione provident earum velit corrupti. Voluptate provident iure perspiciatis, aperiam odio consequatur necessitatibus deserunt tempore alias iusto cupiditate sint quam corrupti in, eligendi laboriosam blanditiis.</p>
			<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Ducimus, culpa nam quia possimus magni minus voluptatibus ab.</p>
		</div>
	</div>
</div>
!

CSS 

              
                @import url('https://fonts.googleapis.com/css2?family=Oxygen+Mono&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Oswald:wght@300&display=swap');

/* Variables */
:root {
  --bg-selected: rgba(0,0,0,0.03);
  --bt-text: #3F1D35;
  --bt-text-selected: #663399;
  --bt-focus: rgba(0,0,0,0.06);
  --text: #454746;
  --border-color: grey;

  font-size: 62.5%;
  box-sizing: border-box;
}

/* Global */
html {
  /* vendor prefixes for box-sizing */
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;

  /* for gradient backgounds */
  min-height: 100%;
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
  background-repeat: no-repeat;
}

*, *:before, *:after {
  -webkit-box-sizing: inherit;
  -moz-box-sizing: inherit;
  box-sizing: inherit;
  }

body {
  font-family: 'Oswald', sans-serif;
  font-size: 1.8rem;
  line-height: 1.6;
  background: linear-gradient(to right, #eefcff, #fff9fa);
}

/* TABS */
.wrapper {
  max-width: 1000px;
  margin: 4rem auto;
  padding: 2rem;
}

.tabs {
  display: grid;
  position: relative;
}

[role="tablist"] {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

[role="tabpanel"] {
  background: var(--bg-selected);
  padding: 2rem;
  min-height: 50vh;
  color: var(--text);

  border-right: 2px solid var(--border-color);
  border-left: 2px solid var(--border-color);
  border-bottom: 2px solid var(--border-color);
}

button {
  font-family: 'Oxygen Mono', monospace;
  font-weight: 600;
  font-size: 2rem;
  letter-spacing: 0.9rem;
  padding: 1rem;
  background: transparent;
  color: var(--bt-text);
  border: 0;
  border-radius: 5px 5px 0 0;
  border-bottom: 2px solid var(--border-color);
  cursor: pointer;
  /* remove the default margin on buttons in Safari */
  margin: 0;
}

button[aria-selected="true"] {
  background: var(--bg-selected);
  color: var(--bt-text-selected);

  border-top: 2px solid var(--border-color);
  border-left: 2px solid var(--border-color);
  border-right: 2px solid var(--border-color);
  border-bottom: 0;
	outline: 0;
}

button[aria-selected="false"]:hover {
  font-size: 2.1rem;
}

/* replace the dotted outline for tab users with a semi-transparent background */
button:focus {
  outline: 0;
  background: var(--bt-focus);
}
button::-moz-focus-inner {
  border:0;
  background: var(--bt-focus);
}

/* Media queries */
@media (max-width: 660px) {
  .wrapper {
    margin: 4rem auto;
    padding: 1rem;
  }

  button {
    border: 0;
    border-radius: 5px 5px 5px 5px;
  }

  button[aria-selected="true"] {
		border: 2px solid var(--border-color);
  }

  [role="tablist"] {
    grid-template-columns: repeat(1, minmax(200px, 1fr));
  }

  [role="tabpanel"] {
    margin-top: 10px;
    border: 2px solid var(--border-color);
  }
}
!

JS 

              
                const tabs = document.querySelector('.tabs');
const tabButtons = tabs.querySelectorAll('[role="tab"]');
const tabPanels = Array.from(tabs.querySelectorAll('[role="tabpanel"]'));

function handleTabClick(event) {
  // hide all tab panels
  tabPanels.forEach(panel => {
    panel.hidden = true;
  });

  // mark all tab buttons as unselected
  tabButtons.forEach(tab => {
    tab.setAttribute('aria-selected', false);
  });

  // mark the clicked tab as selected
  event.currentTarget.setAttribute('aria-selected', true);

  // find the associated tab panel and show it - associated by "aria-labelledby"
  const { id } = event.currentTarget;

  const tabPanel = tabPanels.find(
    panel => panel.getAttribute('aria-labelledby') === id
  );
  tabPanel.hidden = false;
}

tabButtons.forEach(button => button.addEventListener('click', handleTabClick));
!
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