Generated by SassMeister.com.

SassMeister-input-HTML.html

 <button class="in_progress">get videos</button >

SassMeister-input.scss

// ----
// Sass (v3.4.11)
// Compass (v1.0.3)
// ----

// ----
// Sass (v3.4.11)
// Compass (v1.0.3)
// ----

@import "compass";

$Color1: #95C2A1; /* #CADDCF; */
$Color2: #1BBE9E;
$Color3: darken(#3C7670,10%);

body {
	background: #3C7670;
	color:#FFF;
	font-family: 'Montserrat', sans-serif;
}

button {
  font-size:28px;
	display: block;
	margin: 1em auto;
	background: #1BBE9E;
	border: 1px solid #1BBE9E;
	color: #FFF;
	text-transform: uppercase;
	padding: .7em 2em;
}

@include keyframes(tumblr_progress) {
  0%   {background: $Color1;}
  25%  {background: $Color2;}
  50%   {background: $Color3;}
  75%  {background: $Color2;}
  100%   {background: $Color1;}
};

.in_progress {
  @include animation(tumblr_progress 5s infinite)
}

SassMeister-output.css

/* #CADDCF; */
body {
  background: #3C7670;
  color: #FFF;
  font-family: 'Montserrat', sans-serif;
}

button {
  font-size: 28px;
  display: block;
  margin: 1em auto;
  background: #1BBE9E;
  border: 1px solid #1BBE9E;
  color: #FFF;
  text-transform: uppercase;
  padding: .7em 2em;
}

@-moz-keyframes tumblr_progress {
  0% {
    background: #95C2A1;
  }
  25% {
    background: #1BBE9E;
  }
  50% {
    background: #2b5450;
  }
  75% {
    background: #1BBE9E;
  }
  100% {
    background: #95C2A1;
  }
}
@-webkit-keyframes tumblr_progress {
  0% {
    background: #95C2A1;
  }
  25% {
    background: #1BBE9E;
  }
  50% {
    background: #2b5450;
  }
  75% {
    background: #1BBE9E;
  }
  100% {
    background: #95C2A1;
  }
}
@keyframes tumblr_progress {
  0% {
    background: #95C2A1;
  }
  25% {
    background: #1BBE9E;
  }
  50% {
    background: #2b5450;
  }
  75% {
    background: #1BBE9E;
  }
  100% {
    background: #95C2A1;
  }
}
.in_progress {
  -moz-animation: tumblr_progress 5s infinite;
  -webkit-animation: tumblr_progress 5s infinite;
  animation: tumblr_progress 5s infinite;
}

SassMeister-rendered.html

 <button class="in_progress">get videos</button >

http://sassmeister.com/gist/759a77f107f50d543cbc