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.typing-indicator {
  $ti-color-bg: #E6E7ED;
  background-color: $ti-color-bg;
  width: auto;
  border-radius: 50px;
  padding: 20px;
  display: table;
  margin: 0 auto;
  position: relative;
  animation: 2s bulge infinite ease-out;
  &:before, &:after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: -2px;
    height: 20px;
    width: 20px;
    border-radius: 50%;
    background-color: $ti-color-bg;
  }
  &:after {
    height: 10px;
    width: 10px;
    left: -10px;
    bottom: -10px;
  }
  span {
    height: 15px;
    width: 15px;
    float: left;
    margin: 0 1px;
    background-color: #9E9EA1;
    display: block;
    border-radius: 50%;
    opacity: 0.4;
    @for $i from 1 through 3 {
      &:nth-of-type(#{$i}){
        animation: 1s blink infinite ($i * .3333s);
      }
    }
  }
}
@keyframes blink{
  50% {
    opacity: 1;
  }
}
@keyframes bulge{
  50% {
    transform: scale(1.05);
  }
}
// vertically center demo 
html {
  display: table;
  height: 100%;
  width: 100%;
}
body {
  display: table-cell;
  vertical-align: middle;
}

<div class="typing-indicator">
  <span></span>
  <span></span>
  <span></span>
</div>

.typing-indicator {
  background-color: #E6E7ED;
  width: auto;
  border-radius: 50px;
  padding: 20px;
  display: table;
  margin: 0 auto;
  position: relative;
  -webkit-animation: 2s bulge infinite ease-out;
          animation: 2s bulge infinite ease-out;
}
.typing-indicator:before, .typing-indicator:after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: -2px;
  height: 20px;
  width: 20px;
  border-radius: 50%;
  background-color: #E6E7ED;
}
.typing-indicator:after {
  height: 10px;
  width: 10px;
  left: -10px;
  bottom: -10px;
}
.typing-indicator span {
  height: 15px;
  width: 15px;
  float: left;
  margin: 0 1px;
  background-color: #9E9EA1;
  display: block;
  border-radius: 50%;
  opacity: 0.4;
}
.typing-indicator span:nth-of-type(1) {
  -webkit-animation: 1s blink infinite 0.3333s;
          animation: 1s blink infinite 0.3333s;
}
.typing-indicator span:nth-of-type(2) {
  -webkit-animation: 1s blink infinite 0.6666s;
          animation: 1s blink infinite 0.6666s;
}
.typing-indicator span:nth-of-type(3) {
  -webkit-animation: 1s blink infinite 0.9999s;
          animation: 1s blink infinite 0.9999s;
}

@-webkit-keyframes blink {
  50% {
    opacity: 1;
  }
}

@keyframes blink {
  50% {
    opacity: 1;
  }
}
@-webkit-keyframes bulge {
  50% {
    -webkit-transform: scale(1.05);
            transform: scale(1.05);
  }
}
@keyframes bulge {
  50% {
    -webkit-transform: scale(1.05);
            transform: scale(1.05);
  }
}
html {
  display: table;
  height: 100%;
  width: 100%;
}

body {
  display: table-cell;
  vertical-align: middle;
}