var ccc = 'rgb(204, 204, 204)';
[].slice.call(document.querySelectorAll('table, td')).forEach(function(element){
    var style = document.defaultView.getComputedStyle(element, null);
    if (style.borderTopColor == ccc) element.style.borderTop = 'none';
    if (style.borderRightColor == ccc) element.style.borderRight = 'none';
    if (style.borderBottomColor == ccc) element.style.borderBottom = 'none';
    if (style.borderLeftColor == ccc) element.style.borderLeft = 'none';
});