3

I want to have an expanding radius that starts from the center of the div instead of it starting on the top left of the div.

Imagine the button has a pulsing outline that goes outwards. That pulsing outline should start from the middle of the div and go out.

See example here: https://jsbin.com/dinehoqaro/edit?html,css,output

You can see that the expansion is starting from the top left. 

.circle {
  background-color: white;
  border: 1px solid red;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  animation: pulse 1s infinte;
  -webkit-animation: pulse 1.2s infinite;
}
button {
  background-color: green;
  border: none;
  border-radius: 50%;
  width: 50px;
  height: 50px;
}
@-webkit-keyframes pulse {
  from {
    width: 50px;
    height: 50px;
  }
  to {
    width: 100px height: 100px;
  }
}
@keyframes pulse {
  from {
    width: 50px;
    height: 50px;
  }
  to {
    width: 100px;
    height: 100px;
  }
}
<div class="circle"><button>click here</button></div>
Michael Benjamin
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Richard Bustos
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1 Answers1

6

Here's a general solution using CSS flexbox, transform and pseudo-elements.

body {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: lightyellow;
  height: 100vh;
  margin: 0;
}
#container {
  display: flex;
  align-items: center;
  justify-content: center;
}
.sphere {
  display: flex;
  background: lightblue;
  border-radius: 300px;
  height: 100px;
  width: 100px;
}
#container::after {
  display: flex;
  background: lightpink;
  border-radius: 300px;
  height: 250px;
  width: 250px;
  animation: pulsate 2.5s ease-out;
  animation-iteration-count: infinite;
  opacity: 0.0;
  content: "";
  z-index: -1;
  margin: auto;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
}
@keyframes pulsate {
  0% {
    transform: scale(0.1, 0.1);
    opacity: 0.0;
  }
  50% {
    opacity: 1.0;
  }
  100% {
    transform: scale(1.2, 1.2);
    opacity: 0.0;
  }
}
<div id="container">
  <div class="sphere"></div>
</div>

jsFiddle

Also see this awesome solution by @harry: How to create a pulsing glow ring animation in CSS?

Michael Benjamin
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  • This is exactly what im looking for! Is using flexbox the only solution? i would need it to support older broswers – Richard Bustos Oct 16 '15 at 00:56
  • The flexboxes are used for easy centering. You can also center using traditional methods. Here's a quick outtine using positioning properties (flexboxes removed): http://jsfiddle.net/52grpf7L/2/ – Michael Benjamin Oct 16 '15 at 01:03