Gantt chart with double axes and padding

The code below is the source for this graph.

<?php
// Gantt chart with double axes and padding
require_once 'SVGGraph/autoloader.php';

$options = [
  'auto_fit' => true,
  'structure' => [
    'key' => 0, 'axis_text' => 1,
    'value' => [2, 4, 6, 8],
    'end' => [3, 5, 7, 9],
    'complete' => ['c1', 'c2', 'c3', 'c4'],
    'milestone' => ['m1', 'm2', 'm3', 'm4'],
    'group' => 'g',
  ],
  'data_label_font_weight' => 'bold',
  'gantt_today_date' => '2022-04-19',
  'bar_space' => 20,
  'axis_double_x' => true,
  'axis_double_y' => true,
  'axis_pad_top' => 20,
  'axis_pad_left' => 20,
  'axis_pad_right' => 20,
  'axis_pad_bottom' => 20,
];

$values = [
  [0, 'Big project', 'g' => 'top'],

  [1, 'First part', 'g' => '*'],
  [2, 'Repeated', '2022-04-01', '2022-04-05', '2022-04-08', '2022-04-12',
  'c1' => 80, 'c2' => 10],
  [3, 'Second task', '2022-04-05', '2022-04-20', '2022-04-25',
  'c1' => 40, 'm2' => true],

  [4, 'Second part', 'g' => '*', 'd' => 3],
  [5, 'Important dates', '2022-03-29', null, '2022-04-12', null, '2022-04-26',
  'm1' => true, 'm2' => true, 'm3' => true, 'm4' => true],
  [6, 'Third task', '2022-05-02', '2022-05-17', '2022-05-19', '2022-05-20'],
  [7, 'Final task', '2022-05-16', '2022-05-20', '2022-04-12',
  'm2' => true],
];

$graph = new Goat1000\SVGGraph\SVGGraph(670, 'auto', $options);
$graph->values($values);
$graph->colourRangeHexHSL(0, '#c50', '#c59');
$graph->colourRangeHexHSL(1, '#6a0', '#6a9');
$graph->render('GanttChart');

Please note: the source code above comes from a script used to generate one of the example graphs on the site. This is simply a wrapper page to apply highlighting and make the source code easier to read, so there is no content here to describe what the source code is doing.