Parametrising an internal border

// 2021, use it at your own risk;
if (app.documents.length > 0) {
    var myDocument = app.activeDocument;
// set to pixels;
    var originalRulerUnits = app.preferences.rulerUnits;
    app.preferences.rulerUnits = Units.PIXELS;
// get dimensions;
    var theWidth = myDocument.width;
    var theHeight = myDocument.height;
    var theOffset = theWidth*0.0333333;
    var theStroke = theWidth*0.01;
    myDocument.selection.select([[theOffset, theOffset], [theWidth-theOffset, theOffset], [theWidth-theOffset, theHeight-theOffset], [theOffset, theHeight-theOffset]], SelectionType.REPLACE, 0, false)
    myDocument.selection.select([[theOffset+theStroke, theOffset+theStroke], [theWidth-theOffset-theStroke, theOffset+theStroke], [theWidth-theOffset-theStroke, theHeight-theOffset-theStroke], [theOffset+theStroke, theHeight-theOffset-theStroke]], SelectionType.DIMINISH, 0, false)
    createSolidColorLayer (0, 0, 0);
// reset;
    app.preferences.rulerUnits = originalRulerUnits;
};
////// make solid color layer //////
function createSolidColorLayer (theRed, theGreen, theBlue) {
// create solid color layer;
// =======================================================
    var idMk = charIDToTypeID( "Mk  " );
        var desc8 = new ActionDescriptor();
        var idnull = charIDToTypeID( "null" );
            var ref6 = new ActionReference();
            var idcontentLayer = stringIDToTypeID( "contentLayer" );
            ref6.putClass( idcontentLayer );
        desc8.putReference( idnull, ref6 );
        var idUsng = charIDToTypeID( "Usng" );
            var desc9 = new ActionDescriptor();
            var idType = charIDToTypeID( "Type" );
                var desc10 = new ActionDescriptor();
                var idClr = charIDToTypeID( "Clr " );
                    var desc11 = new ActionDescriptor();
                    var idRd = charIDToTypeID( "Rd  " );
                    desc11.putDouble( idRd, theRed );
                    var idGrn = charIDToTypeID( "Grn " );
                    desc11.putDouble( idGrn, theGreen );
                    var idBl = charIDToTypeID( "Bl  " );
                    desc11.putDouble( idBl, theBlue );
                var idRGBC = charIDToTypeID( "RGBC" );
                desc10.putObject( idClr, idRGBC, desc11 );
            var idsolidColorLayer = stringIDToTypeID( "solidColorLayer" );
            desc9.putObject( idType, idsolidColorLayer, desc10 );
        var idcontentLayer = stringIDToTypeID( "contentLayer" );
        desc8.putObject( idUsng, idcontentLayer, desc9 );
    executeAction( idMk, desc8, DialogModes.NO );
    return activeDocument.activeLayer
    };