Custom Theme for new Filter Pane

Posting here working code for other's references.

{
  "name": "Filter Pane Theme Sample",
  "visualStyles": {
    "page": {
      "*": {
        "outspacePane": [
          {
            "backgroundColor": { "solid": { "color": "#0000ff" } },
            "foregroundColor": { "solid": { "color": "#00ff00" } },
            "transparency": 50,
            "titleSize": 35,
            "headerSize": 8,
            "fontFamily": "Georgia",
            "border": true,
            "borderColor": { "solid": { "color": "#ff0000" } }
          }
        ],
        "filterCard": [
          {
            "$id": "Applied",
            "transparency": 0,
            "backgroundColor": { "solid": { "color": "#ff0000" } },
            "foregroundColor": { "solid": { "color": "#45f442" } },
            "textSize": 30,
            "fontFamily": "Arial",
            "border": true,
            "borderColor": { "solid": { "color": "#ffffff" } },
            "inputBoxColor": { "solid": { "color": "#C8C8C8" } }
          },
          {
            "$id": "Available",
            "transparency": 40,
            "backgroundColor": { "solid": { "color": "#00ff00" } },
            "foregroundColor": { "solid": { "color": "#ffffff" } },
            "textSize": 10,
            "fontFamily": "Times New Roman",
            "border": true,
            "borderColor": { "solid": { "color": "#123456" } },
            "inputBoxColor": { "solid": { "color": "#777777" } }
          }
        ]
      }
    }
  }
}

Kudos and thanks to Anonymous for the initial link that led to this solution.