mapcomplete/assets/layers/left_right_style/left_right_style.json

{
    "id": "left_right_style",
    "description": "Special meta-style which will show one single line, either on the left or on the right depending on the id. This is used in the small popups with left_right roads",
    "source": {
        "osmTags": {
            "or": [
                "id=left",
                "id=right"
            ]
        }
    },
    "mapRendering": [
        {
            "width": 15,
            "color": {
                "render": "#ff000088",
                "mappings": [
                    {
                        "if": "id=left",
                        "then": "#0000ff88"
                    }
                ]
            },
            "offset": {
                "render": "-15",
                "mappings": [
                    {
                        "if": "id=right",
                        "then": "15"
                    }
                ]
            }
        }
    ]
}