Preserve pixelation when scaling pixel art with CSS - https://builtvisible.com/image-scaling-in-css/

preserve-pixelation.scss

@mixin pixelated {
  -ms-interpolation-mode: nearest-neighbor;  // IE 7+ (non-standard property)
  image-rendering: -webkit-optimize-contrast; // Safari 6, UC Browser 9.9
  image-rendering: -webkit-crisp-edges; // Safari 7+
  image-rendering: -moz-crisp-edges; // Firefox 3.6+
  image-rendering: -o-crisp-edges; // Opera 12
  image-rendering: pixelated; // Chrome 41+ and Opera 26+
}