Help improving script

I have this script. I need that the cell data changes to white when the cell is red, otherwise stay black. If the cell doesn't have any data the cell background should be black 20%. Hope someone can help me!

app.doScript(main, ScriptLanguage.JAVASCRIPT, undefined, UndoModes.ENTIRE_SCRIPT, "Conditional cell formatting");
function main() {
    sel = app.selection[0];
	var cells = sel.cells
    // create color swatches
    var red = swatchCreator("Red Cell", [210,35,42]);
    var yellow = swatchCreator("Amber", [0,51,99,0]);
    var green = swatchCreator("Green", [69,8,87,0]);
    for (var c = 0; c < cells.length; c++) {
		var cc = cells[c].texts[0].contents.split("%")
		var cellValue = parseInt(cc[0])
		isNaN(cellValue) && cellValue = 0
		if (cellValue < 80) {
             cells[c].fillColor = red; 
             cells[c].texts[0].fillColor = "Paper";
            continue;
        }
        if (cellValue >= 80 && cellValue < 95) {
            cells[c].fillColor = yellow;
            continue;
        }
        if (cellValue >= 95) {
            cells[c].fillColor = green;
        }
    }
}
function swatchCreator(colorname, values) {
    var swatch = app.activeDocument.colors.item(colorname);
    if (!swatch.isValid) {
        swatch = app.activeDocument.colors.add({
            name: colorname,
            model: ColorModel.PROCESS,
            space: ColorSpace.CMYK,
            colorValue: values
            });

    }

    return swatch;

}