How TO - Vertical Tabs

<div class="tab">
  <button class="tablinks" onclick="openCity(event,
  'London')">London</button>
  <button class="tablinks" onclick="openCity(event,
  'Paris')">Paris</button>
  <button class="tablinks" onclick="openCity(event,
  'Tokyo')">Tokyo</button>

</div>

<div id="London" class="tabcontent">
  <h3>London</h3>
 
<p>London is the capital city of England.</p>
</div>

<div
id="Paris" class="tabcontent">
  <h3>Paris</h3>
  <p>Paris
is the capital of France.</p>
</div>

<div id="Tokyo" class="tabcontent">
 
<h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

  * {box-sizing: border-box}

/* Style the tab */
.tab {
  float: left;
  border: 1px solid #ccc;

    background-color: #f1f1f1;
 
  width: 30%;
  height: 300px;
}

/* Style the buttons that are used to open the tab content */
.tab button {

   
  display: block;
  background-color: inherit;
 
  color: black;
  padding: 22px 16px;
 
  width: 100%;
  border: none;
 
  outline: none;
  text-align: left;
  cursor: pointer;
  transition: 0.3s;
}

/* Change
  background color of buttons on hover */
.tab button:hover {
  background-color: #ddd;
}

/* Create an active/current "tab button"
  class */
.tab button.active {
  background-color:
  #ccc;
}

/* Style the tab content */
.tabcontent {
 
  float: left;
  padding: 0px 12px;
 
  border: 1px solid #ccc;
  width: 70%;
  border-left: none;

    height: 300px;
}

function openCity(evt, cityName) {
  // Declare all
variables
  var i, tabcontent, tablinks;

 
// Get all elements with class="tabcontent" and hide them
  tabcontent
= document.getElementsByClassName("tabcontent");
  for (i = 0; i < tabcontent.length; i++) {

      tabcontent[i].style.display = "none";
  }

  // Get all elements with class="tablinks" and remove
the class "active"

   
tablinks = document.getElementsByClassName("tablinks");
  for (i = 0; i <
tablinks.length; i++) {
   
tablinks[i].className = tablinks[i].className.replace(" active", "");

    }

  // Show the current tab, and add an "active" class to
the link that opened the tab

  document.getElementById(cityName).style.display = "block";

  evt.currentTarget.className += " active";
}