toDataURL css isn't captured code example

Example 1: convert canvas to DataUrl and insert image in google sheet

function savejSigToSht() {

        var dataURL = canvas.toDataURL('image/png');

        google.script.run.insertSig(dataURL);
        google.script.host.close();
    }

Example 2: convert canvas to DataUrl and insert image in google sheet

function insertSiginSht(blb) {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheets()[0];
  sheet.insertImage(blb, 2,2);

}