Drawing charts inside hidden divs causes the Visualization API's dimension detection algorithms to break, which is why your charts are messed up. The fix is to draw the charts while the divs are visible, then hide the divs after the charts have drawn. You can use "ready" event handlers for your charts to accomplish this:
google.visualization.events.addListener(chart, 'ready', function () {
document.querySelector('#myChartDiv').style.display = 'none';
});