Thank you, JuanC for your help.
the first issue is solved.
I think you got me wrong with the second issue - what I want is this:
Imagine I have a div
<div style="width:555px;background-color:#FF0000;" id="mypiechart"></div>
I want to create a chart in this div.
But I want the chart to have any background styling, nor a border, nor a gradient, just as it.
If such "transparency" is not possible, it would be also ok if the chart background is just simple unicolor red with NO border, NO gradient, etc.
See attachment below.