alization elements
    container = svg.append("g")
      .attr("class", "container");

    // Create group for links and nodes and save references
    linksGroup = container.append("g").attr("class", "links");
    nodesGroup = container.append("g").attr("class", "nodes");

    // Create a gradient definition for links
    const defs = svg.append("defs");

    // Create a glow filter definition (moved to initialization to fix clipping)
    const glow = defs.append("filter")
      .attr("id", "glow")
      .a