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htmlcsscss-animationsradial-gradients

CSS animation not smooth with radial-gradient background

I am trying to create a pulsating circular background with smooth edges. For the circle with smooth edges I am using this CSS code:

background: radial-gradient(black, black, transparent, transparent);

Using my code below works well to animate the background-color. However, as soon as I replace the background-color with this radial-gradient background the animation jumps and is no longer smooth. The behavior is consistent over multiple Browsers. This is a minimal working example of the issue I am having:

.global {
  background: lightskyblue;
}

.silver {
  // background: radial-gradient(black, black, transparent, transparent);
  animation: pulse 3s infinite;
}

@keyframes pulse {
  0%,
  100% {
    // background-color: black;
    background: radial-gradient(black, transparent, transparent, transparent);
  }
  50% {
    // background-color: white;
    background: radial-gradient(black, black, transparent, transparent);
  }
}
<body class="global">
  <img src="pngwave.png" alt="test" class="silver" />
</body>

I have found this Stackoverflow question which is similar but did not help me solve my problem.

Solution

  • You need to animate the background-size

    .box {
  width: 200px;
  height: 200px;
  background: radial-gradient(farthest-side,black, transparent) center no-repeat;
  animation:pulse 2s linear infinite alternate;
}
@keyframes pulse{
  from {
    background-size:50% 50%;
  }
  to {
    background-size:100% 100%;
  }
}
    <div class="box"></div>