<div class="content">
  <div class="buttons">
  <button class="button" onclick="horizontalTb()">horizontal-tb</button> 
  <button class="button" onclick="verticalRl()">vertical-rl</button>  
  <button class="button" onclick="verticalLr()">vertical-lr</button> 
  </div>

  <div id="ex" class="ex">
    <div id="text">CSS </br>writing-mode </br>Property</div>
  </div>
</br>
  <div class="col"><h2>CSS Code:</h2><p id="code">CSS code</p>
</div>
</div>

body {
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.content {
  position: relative;
}

.buttons {
  position: relative;
  left:-200px;
  z-index:1;
  top:95px;
}

button {
  background-color: #333;
  color: white;
  border: none;
  display: block;
  padding:5px;
  width: 100px;
  margin:5px;
  transition: .2s;
  font-weight: bold;
}

button:hover {
  background-color: white;
  color: #333;
}

.col {
  position: relative;
  font-weight: bold;
  font-size:15px;
  width: 100%;
  left:-200px;
  top:0;
}

#text {
  position: absolute;
  font-size:35px;
  font-family: arial;
}

.ex {
  position: sticky;
  width: 280px;
  top:0;
  left:20%;
  background-color: #f5f3f4;
  height:200px;
}

function horizontalTb() {
 document.getElementById("ex").style.writingMode="horizontal-tb" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "writing-mode: horizontal-tb;") {
    x.innerHTML = "writing-mode: horizontal-tb;";
  } else {
    x.innerHTML = "writing-mode: horizontal-tb;";
  }
}

function verticalRl() {
 document.getElementById("ex").style.writingMode="vertical-rl" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "writing-mode: vertical-rl;") {
    x.innerHTML = "writing-mode: vertical-rl;";
  } else {
    x.innerHTML = "writing-mode: vertical-rl;";
  }
}

function verticalLr() {
 document.getElementById("ex").style.writingMode="vertical-lr" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "writing-mode: vertical-lr;") {
    x.innerHTML = "writing-mode: vertical-lr;";
  } else {
    x.innerHTML = "writing-mode: vertical-lr;";
  }
}