var custom = new GC.Spread.Sheets.Theme("CustomTheme");
custom.colors().accent1("red");
custom.colors().accent6("green");
custom.colors().textColor1("orange");
activeSheet.currentTheme(custom);
activeSheet.getCell(0, 0).backColor("accent 1");
activeSheet.getCell(1, 0).backColor("accent 1 30");