Why is this button not clickable?

Question

Why is the button not clickable in this code snippet?

How do I make it clickable?

Is JavaScript needed to make the button clickable? If I use the <button> tag then is it not clickable?

Is the <button> not working because it is on an animated background?

Check .btn-blue; is there any code missing?

@import url('https://fonts.googleapis.com/css?family=Exo:400,700');
* {
  margin: 0px;
  padding: 0px;
}

body {
  font-family: 'Exo', sans-serif;
}

.context {
  width: 100%;
  position: absolute;
  top: 50vh;
}

.context h1 {
  text-align: center;
  color: #fff;
  font-size: 50px;
}

.area {
  background: #4e54c8;
  background: -webkit-linear-gradient(to left, #8f94fb, #4e54c8);
  width: 100%;
  height: 100vh;
}

.circles {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.circles li {
  position: absolute;
  display: block;
  list-style: none;
  width: 20px;
  height: 20px;
  background: rgba(255, 255, 255, 0.2);
  animation: animate 25s linear infinite;
  bottom: -150px;
}

.bk {
  position: relative;
}

.btn-blue {
  background-color: red;
  border-radius: 12px;
  border: 1px transparent solid;
  /* transparent border */
  color: white;
  padding: 13px 30px;
  /* remove 2px as we are now using the border */
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 19px;
  opacity: 0.6;
  cursor: pointer;
}

.btn-blue:hover {
  opacity: 1;
  background-color: blue;
  border: 1px #99ccff solid;
}

.btn-blue:active {
  background-color: #00CCC0;
  border: 1px #000000 solid;
}

.circles li:nth-child(1) {
  left: 25%;
  width: 80px;
  height: 80px;
  animation-delay: 0s;
}

.circles li:nth-child(2) {
  left: 10%;
  width: 20px;
  height: 20px;
  animation-delay: 2s;
  animation-duration: 12s;
}

.circles li:nth-child(3) {
  left: 70%;
  width: 20px;
  height: 20px;
  animation-delay: 4s;
}

.circles li:nth-child(4) {
  left: 40%;
  width: 60px;
  height: 60px;
  animation-delay: 0s;
  animation-duration: 18s;
}

.circles li:nth-child(5) {
  left: 65%;
  width: 20px;
  height: 20px;
  animation-delay: 0s;
}

.circles li:nth-child(6) {
  left: 75%;
  width: 110px;
  height: 110px;
  animation-delay: 3s;
}

.circles li:nth-child(7) {
  left: 35%;
  width: 150px;
  height: 150px;
  animation-delay: 7s;
}

.circles li:nth-child(8) {
  left: 50%;
  width: 25px;
  height: 25px;
  animation-delay: 15s;
  animation-duration: 45s;
}

.circles li:nth-child(9) {
  left: 20%;
  width: 15px;
  height: 15px;
  animation-delay: 2s;
  animation-duration: 35s;
}

.circles li:nth-child(10) {
  left: 85%;
  width: 150px;
  height: 150px;
  animation-delay: 0s;
  animation-duration: 11s;
}

@keyframes animate {
  0% {
    transform: translateY(0) rotate(0deg);
    opacity: 1;
    border-radius: 0;
  }
  100% {
    transform: translateY(-1000px) rotate(720deg);
    opacity: 0;
    border-radius: 50%;
  }
}

<div class="context">
  <h1>Pure Css Animated Background</h1>
  <center> <a class="btn-blue" href="google.com">Start Now</a></center>
</div>


<div class="area">
  <ul class="circles">
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
  </ul>
</div>

Answer 1

First, you need to add "http://" or "https://" to the beginning of absolute URLs.

Second, you need to add the CSS in the previous answer.

Third, you need to use target="_blank" in order for the link to work with the code snippet.

* {
  margin: 0px;
  padding: 0px;
}

body {
  font-family: 'Exo', sans-serif;
}

.context {
  width: 100%;
  position: absolute;
  top: 50vh;
}

.context {
z-index: 2;
}

.context h1 {
  text-align: center;
  color: #fff;
  font-size: 50px;
}

.area {
  background: #4e54c8;
  background: -webkit-linear-gradient(to left, #8f94fb, #4e54c8);
  width: 100%;
  height: 100vh;
}

.circles {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.circles li {
  position: absolute;
  display: block;
  list-style: none;
  width: 20px;
  height: 20px;
  background: rgba(255, 255, 255, 0.2);
  animation: animate 25s linear infinite;
  bottom: -150px;
}

.bk {
  position: relative;
}

.btn-blue {
  background-color: red;
  border-radius: 12px;
  border: 1px transparent solid;
  /* transparent border */
  color: white;
  padding: 13px 30px;
  /* remove 2px as we are now using the border */
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 19px;
  opacity: 0.6;
  cursor: pointer;
}

.btn-blue:hover {
  opacity: 1;
  background-color: blue;
  border: 1px #99ccff solid;
}

.btn-blue:active {
  background-color: #00CCC0;
  border: 1px #000000 solid;
}

.circles li:nth-child(1) {
  left: 25%;
  width: 80px;
  height: 80px;
  animation-delay: 0s;
}

.circles li:nth-child(2) {
  left: 10%;
  width: 20px;
  height: 20px;
  animation-delay: 2s;
  animation-duration: 12s;
}

.circles li:nth-child(3) {
  left: 70%;
  width: 20px;
  height: 20px;
  animation-delay: 4s;
}

.circles li:nth-child(4) {
  left: 40%;
  width: 60px;
  height: 60px;
  animation-delay: 0s;
  animation-duration: 18s;
}

.circles li:nth-child(5) {
  left: 65%;
  width: 20px;
  height: 20px;
  animation-delay: 0s;
}

.circles li:nth-child(6) {
  left: 75%;
  width: 110px;
  height: 110px;
  animation-delay: 3s;
}

.circles li:nth-child(7) {
  left: 35%;
  width: 150px;
  height: 150px;
  animation-delay: 7s;
}

.circles li:nth-child(8) {
  left: 50%;
  width: 25px;
  height: 25px;
  animation-delay: 15s;
  animation-duration: 45s;
}

.circles li:nth-child(9) {
  left: 20%;
  width: 15px;
  height: 15px;
  animation-delay: 2s;
  animation-duration: 35s;
}

.circles li:nth-child(10) {
  left: 85%;
  width: 150px;
  height: 150px;
  animation-delay: 0s;
  animation-duration: 11s;
}

@keyframes animate {
  0% {
    transform: translateY(0) rotate(0deg);
    opacity: 1;
    border-radius: 0;
  }
  100% {
    transform: translateY(-1000px) rotate(720deg);
    opacity: 0;
    border-radius: 50%;
  }
}

<div class="context">
  <h1>Pure Css Animated Background</h1>
  <center> <a class="btn-blue" href="https://google.com" target="_blank">Start Now</a></center>
</div>


<div class="area">
  <ul class="circles">
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
  </ul>
</div>

Answer 2

Add this to your css file:

.context{
  z-index: 2;
}