Karabiner Elements complex modification to map Ctrl-PageUp/PageDown tab navigation to Safari Ctrl-Shift-Tab/Ctrl-Tab navigation

complex-modification.json

{
  "title": "Map Ctrl-PageUp and Ctrl-PageDown to Ctrl-Tab and Ctrl-Shift-Tab",
  "rules": [
    {
      "description": "Map Ctrl-PageUp to Ctrl-Shift-Tab",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "modifiers": {
              "mandatory": [
                "left_control"
              ]
            },
            "key_code": "page_up"
          },
          "to": [
            {
              "repeat": true,
              "key_code": "tab",
              "modifiers": [
                "left_control",
                "left_shift"
              ]
            }
          ]
        }
      ]
    },
    {
      "description": "Map Ctrl-PageDown to Ctrl-Tab",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "modifiers": {
              "mandatory": [
                "left_control"
              ]
            },
            "key_code": "page_down"
          },
          "to": [
            {
              "repeat": true,
              "key_code": "tab",
              "modifiers": [
                "left_control"
              ]
            }
          ]
        }
      ]
    }
  ]
}