Create an animated "rainbow" button with CSS

Let's discover in this article how to create a "rainbow" button that animates on mouse hover. A modern and sensational effect guaranteed!

Step 1

The HTML code.

<button>
  Click me
</button>

Our HTML code consists of a simple button. We couldn't make it any simpler, could we?

Step 2

Let's style our button.

button {
  padding: 20px 50px;
  font-size: 1.5rem;
  cursor: pointer;
  border: 0px;
  background: transparent;
  position: relative;
  transition: all .2s;
  overflow: hidden;
  color: #fff;
  border-radius: 30px;
  box-shadow: 0px -0px 0px 0px rgba(143, 64, 248, .5), 0px 0px 0px 0px rgba(39, 200, 255, .5);
}

In the previous step, we created a “rainbow” square. It is simply a 400px by 400px square that we offset to the side using the top and left properties to capture the most beautiful part of the gradient.

Step 3

Let's add a rainbow square.

button::after {
  content: '';
  width: 400px;
  height: 400px;
  position: absolute;
  top: -50px;
  left: -100px;
  background-image: linear-gradient(225deg, 
#27d86c 0%, #26caf8 50%, #c625d0 100%);
  z-index: -1;
  transition: all .5s;
}

In this step, we style the button::after pseudo-element to create the rainbow square. This square will serve as the background for our button, and it will not overflow thanks to the overflow: hidden property we added in step 2.

Step 4

Let's add hover effects.

button:hover::after {
  transform: rotate(150deg);
}

button:hover {
  transform: translate(0, -6px);
  box-shadow: 10px -10px 25px 0px rgba(143, 64, 248, .25), -10px 10px 25px 0px rgba(39, 200, 255, .25);
}

Here, we simply rotate our rainbow square to change the gradient displayed in the button's background.
We also take the opportunity to raise it upwards using the transform property and add a more significant shadow using the box-shadow property.