activity-indicator.css

:root {
  --pipColor: #999;
  --pipSize: 8px;
  --pipSpacing: 3px;
}

@keyframes pulse {
  0%, 80%, 100% {
    transform: scale(0.8);
    opacity: 0;
  }
  40% {
    transform: scale(1);
    opacity: 1;
  }
}

.indicator {
  position: relative;
  height: 100%;
  width: 100%;
  min-height: 100px;
}

.inner {
  position: absolute;;
  top: 50%;
  left: 50%;
  display: block;
  margin: 0 auto;
  text-align: center;
  line-height: 0;

  transform: translate(-50%, -50%);
  width: calc(var(--pipSize) * 3 + var(--pipSpacing) * 3);
}

.pip {
  display: inline-block;
  margin: 0 calc(var(--pipSpacing)/2);
  width: var(--pipSize);
  height: var(--pipSize);
  background: var(--pipColor);
  border-radius: 100%;
  animation-fill-mode: both;
  animation: pulse 1.4s infinite ease-in-out;

  &:first-child {
    animation-delay: -0.32s;
  }
  &:nth-child(2) {
    animation-delay: -0.16s;
  }
}

activity-indicator.js

import React from 'react'
import autobind from 'autobind-decorator'
import styleable from 'react-styleable'

import css from './activity-indicator.css'

@styleable(css)
@autobind
export default class ActivityIndicator extends React.Component {
  render() {
    const { css } = this.props

    return (
      <div className={css.indicator}>
        <div className={css.inner}>
          <i className={css.pip} />
          <i className={css.pip} />
          <i className={css.pip} />
        </div>
      </div>
    )
  }
}