<!DOCTYPE html>
<html>
  <head>
    <title>Neva Dataflow Animation</title>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/7.8.5/d3.min.js"></script>
    <style>
      body {
        margin: 0;
        background: #1a1f2c; /* Slightly lighter, more vibrant dark blue */
        font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
          Helvetica, Arial, sans-serif;
      }
      .grid line {
        stroke: #2a3343; /* Brighter grid lines */
        stroke-width: 1px;
      }
  