<div class="sun"></div>

html, body {
  overflow: hidden;
  background: #a02615;
  padding: 0;
  margin: 0;
}

.sun {
  position: absolute;
  top: -75px;
  left: -75px;
  width: 500px;
  height: 500px;
}

.sun-ray {
  width: 250px;
  height: 40px;
  background: url(//sergeche.github.io/gpu-article-assets/images/ray.png) no-repeat;

  /* align rays with sun center */
  position: absolute;
  left: 50%;
  top: 50%;
  margin-top: -20px;
  transform-origin: 0 50%;
  
  /* tell browser to properly optimize compositing */
  will-change: transform;
}

const container = document.querySelector('.sun');
const raysAmount = 12;
const angularVelocity = 0.5;
const rays = createRays(container, raysAmount);

animate();

function animate() {
    rays.forEach(ray => {
        ray.angle += angularVelocity;
        ray.elem.style.transform = `rotate(${ray.angle % 360}deg)`;
    });
    requestAnimationFrame(animate);
}

function createRays(container, amount) {
    const rays = [];
    const rotationStep = 360 / amount;
    while (amount--) {
        const angle = rotationStep * amount;
        const elem = document.createElement('div');
        elem.className = 'sun-ray';
        container.appendChild(elem);
        rays.push({elem, angle});
    }
    return rays;
}