Christophe Yamahata

Here's an equivalent using Observable Plot:

Plot.plot({
  height: 400,
  width: 500,
  color: {
    legend: true,
    label: "intensity",
    scheme: "viridis",
    type: "linear" // alternatively use {typed: true} in the .csv() call
  },
  marks: [
    Plot.rect(surface_plot, {
      x: "x",
      y: "y",
      fill: "z",
      interval: 5,
      inset: -0.5
    })
  ]
})

Thank you Fil. I have updated my notebook accordingly.