<div class="content">
  <div class="buttons">
  <button class="button" onclick="none()">none</button> 
  <button class="button" onclick="hvcolor()">10px 10px red</button>  
  <button class="button" onclick="hvcolor2()">50px 50px red</button> 
  <button class="button" onclick="hvcolorblur()">15px 15px 10px black</button>  
  <button class="button" onclick="hvcolorblur2()">0px 0px 40px black</button> 
    <button class="button" onclick="hvcolorblurspread()">10px 10px 40px 20px black</button> 
    <button class="button" onclick="hvcolorblurspreadinset()">10px 10px 20px black inset</button> 
          
  </div>
<div id="square"></div>
  <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;
}

#square {
  width:100px;
  height: 100px;
  background-color: #0a9396;
  position: relative;
}

.buttons {
  left:-210px;
  position: absolute;
  top:-70px;
  z-index:1;
}

button {
  background-color: #333;
  color: white;
  border: none;
  display: block;
  padding:5px;
  width: 150px;
  margin:5px;
  transition: .2s;
  font-weight: bold;
}

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

.col {
  position: absolute;
  font-weight: bold;
  font-size:15px;
  width: 250px;
  left:150px;
  top:-15px;
}

function none() {
  document.getElementById("square").style.boxShadow="none" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: none;") {
    x.innerHTML = "box-shadow: none;";
  } else {
    x.innerHTML = "box-shadow: none;";
  }
}

function hvcolor() {
  document.getElementById("square").style.boxShadow="10px 10px red" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: 10px 10px red;") {
    x.innerHTML = "box-shadow: 10px 10px red;";
  } else {
    x.innerHTML = "box-shadow: 10px 10px red;";
  }
}

function hvcolor2() {
  document.getElementById("square").style.boxShadow="50px 50px red" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: 50px 50px red;") {
    x.innerHTML = "box-shadow: 50px 50px red;";
  } else {
    x.innerHTML = "box-shadow: 50px 50px red;";
  }
}

function hvcolorblur() {
  document.getElementById("square").style.boxShadow="15px 15px 10px black" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: 15px 15px 10px black;") {
    x.innerHTML = "box-shadow: 15px 15px 10px black;";
  } else {
    x.innerHTML = "box-shadow: 15px 15px 10px black;";
  }
}

function hvcolorblur2() {
  document.getElementById("square").style.boxShadow="0px 0px 40px black" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: 0px 0px 40px black;") {
    x.innerHTML = "box-shadow: 0px 0px 40px black;";
  } else {
    x.innerHTML = "box-shadow: 0px 0px 40px black;";
  }
}

function hvcolorblurspread() {
  document.getElementById("square").style.boxShadow="10px 10px 40px 20px black" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: 10px 10px 40px 20px black;") {
    x.innerHTML = "box-shadow: 10px 10px 40px 20px black;";
  } else {
    x.innerHTML = "box-shadow: 10px 10px 40px 20px black;";
  }
}

function hvcolorblurspreadinset() {
  document.getElementById("square").style.boxShadow="10px 10px 20px black inset" 
  
  var x = document.getElementById("code");
  if (x.innerHTML === "box-shadow: 10px 10px 20px black inset;") {
    x.innerHTML = "box-shadow: 10px 10px 20px black inset;";
  } else {
    x.innerHTML = "box-shadow: 10px 10px 20px black inset;";
  }
}