<style type="text/css">
  #root{
    height: 100%;
    background-color: transparent;
    background-size: 50px 50px;

    /* Transparent grid background */
    background-image:
        linear-gradient(
            0deg,
            transparent 24%,
            rgba(0, 0, 0, .02) 25%,
            rgba(0, 0, 0, .02) 26%,
            transparent 27%,
            transparent 74%,
            rgba(0, 0, 0, .02) 75%,
            rgba(0, 0, 0, .02) 76%,
            transparent 77%,
            transparent
        ),
        linear-gradient(
            90deg,
            transparent 24%,
            rgba(0, 0, 0, .02) 25%,
            rgba(0, 0, 0, .02) 26%,
            transparent 27%,
            transparent 74%,
            rgba(0, 0, 0, .02) 75%,
            rgba(0, 0, 0, .02) 76%,
            transparent 77%, 
            transparent
        );
  }
</style>

Add lighten grid background in preview
[storybook] Add lighten grid background in preview
