Add noise to a background using modest-sized tile, but preventing any noticeable repetition

cicada-noise.css

html {
  background-color: #eed;
  background-image: url(noise.png), url(noise.png), url(noise.png);
  background-size: 79px 79px, 101px 101px, 73px 73px;
  background-position: 0 0, 5px 5px, 11px 11px;
}

noise.png should be 79px by 79px, and lighter than normal, as it will be layered three times. My image of choice has noise in the alpha channel, so that overlapping pixels will combine opacities for more varied results. The color of the image is saturated, full-color noise, so that overlapping pixels combine to produce variety of hue and saturation. The low overall opacity keeps the colors from being noticeable.

Example at http://camenischcreative.com/