An APL document with a gradient background and optional picture. More about APL here https://developer.amazon.com/en-US/docs/alexa/alexa-presentation-language/understand-apl.html.

GradientBackgroundNoPicture.json

{
    "document": {
        "type": "APL",
        "version": "1.4",
        "import": [
            {
                "name": "alexa-layouts",
                "version": "1.2.0"
            }
        ],
        "graphics": {
            "gradientBackground": {
                "type": "AVG",
                "version": "1.1",
                "height": 100,
                "width": 100,
                "scaleTypeHeight": "grow",
                "parameters": [
                    {
                        "name": "gradientFill",
                        "type": "gradient"
                    }
                ],
                "items": [
                    {
                        "type": "path",
                        "pathData": "M0,0 L${width},0 L${width},${height} L0,${height}",
                        "fill": "${gradientFill}"
                    }
                ]
            }
        },
        "mainTemplate": {
            "parameters": [
                "backgroundData"
            ],
            "items": [
                {
                    "type": "Container",
                    "width": "100%",
                    "height": "100%",
                    "items": [
                        {
                            "when": "${backgroundData.pictureSource}",
                            "type": "AlexaBackground",
                            "backgroundImageSource": "${backgroundData.pictureSource}"
                        },
                        {
                            "type": "VectorGraphic",
                            "source": "gradientBackground",
                            "width": "100%",
                            "height": "100%",
                            "scale": "fill",
                            "gradientFill": "${backgroundData.pictureSource ? backgroundData.pictureOverlay : backgroundData.noPictureOverlay}"
                        },
                        {
                            "type": "Container",
                            "position": "absolute",
                            "width": "100%",
                            "height": "100%",
                            "alignItems": "center",
                            "justifyContent": "center",
                            "items": [
                                {
                                    "type": "AlexaHeader",
                                    "headerTitle": "${backgroundData.headlineText}",
                                    "headerAttributionPrimacy": false
                                }
                            ]
                        }
                    ]
                }
            ]
        },
        "layouts": {}
    },
    "datasources": {
        "backgroundData": {
            "headlineText": "Red/Black gradient",
            "pictureSource": "",
            "pictureOverlay": {
                "type": "linear",
                "colorRange": [
                    "rgb(255,0,0,0.2)",
                    "rgb(0,0,0,1.0)"
                ],
                "x1": 0,
                "x2": 1,
                "y1": 0,
                "y2": 1
            },
            "noPictureOverlay": {
                "type": "linear",
                "colorRange": [
                    "rgb(125,0,0,1)",
                    "rgb(10,10,10,1)"
                ],
                "x1": 0,
                "x2": 1,
                "y1": 0,
                "y2": 1
            }
        }
    },
    "sources": {}
}