Change Gravity Forms Spinner to CSS Spinner

functions.php

// Changes Gravity Forms Ajax Spinner (next, back, submit) to a transparent image
// this allows you to target the css and create a pure css spinner like the one used below in the style.css file of this gist.
add_filter( 'gform_ajax_spinner_url', 'spinner_url', 10, 2 );
function spinner_url( $image_src, $form ) {
    return  'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7'; // relative to you theme images folder

}

spinner.html

<div class="spinner">
  <div class="bounce1"></div>
  <div class="bounce2"></div>
  <div class="bounce3"></div>
</div>

style.css

/* Spinner */
.gform_ajax_spinner {
	margin-left: 20px;
	border: 4px solid rgba(255, 255, 255, 0.3);
	border-left: 4px solid rgba(110, 73, 217, 0.7);
	animation: spinner 1.1s infinite linear;
	border-radius: 50%;
	width: 30px;
	height: 30px;
}
@keyframes spinner {
	0% {
		transform: rotate(0deg);
	}
	100% {
		transform: rotate(360deg);
	}
}

/* Spinner from https://tobiasahlin.com/spinkit/ */
.spinner {
  margin: 100px auto 0;
  width: 70px;
  text-align: center;
}

.spinner > div {
  width: 18px;
  height: 18px;
  background-color: #333;

  border-radius: 100%;
  display: inline-block;
  -webkit-animation: sk-bouncedelay 1.4s infinite ease-in-out both;
  animation: sk-bouncedelay 1.4s infinite ease-in-out both;
}

.spinner .bounce1 {
  -webkit-animation-delay: -0.32s;
  animation-delay: -0.32s;
}

.spinner .bounce2 {
  -webkit-animation-delay: -0.16s;
  animation-delay: -0.16s;
}

@-webkit-keyframes sk-bouncedelay {
  0%, 80%, 100% { -webkit-transform: scale(0) }
  40% { -webkit-transform: scale(1.0) }
}

@keyframes sk-bouncedelay {
  0%, 80%, 100% { 
    -webkit-transform: scale(0);
    transform: scale(0);
  } 40% { 
    -webkit-transform: scale(1.0);
    transform: scale(1.0);
  }
}