How to change drop-down menu text color in pyqt5 designer?

Question

Precisely, I have QComboBox in PyQt5 Designer and I would to change drop-down menu/list text color to white. I tried below as given on PyQt5 documentation example, but it only change the selected item text color but not the list in the drop down menu.

QComboBox{
color:#fff;
background:#333;
padding:5px;
}
QComboBox:editable {
background: white;
color:#fff;
}

QComboBox:!editable, QComboBox::drop-down:editable {
 background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1,
                             stop: 0 #E1E1E1, stop: 0.4 #DDDDDD,
                             stop: 0.5 #D8D8D8, stop: 1.0 #D3D3D3);
color:#fff;
}

/* QComboBox gets the "on" state when the popup is open */
QComboBox:!editable:on, QComboBox::drop-down:editable:on {
background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1,
                            stop: 0 #D3D3D3, stop: 0.4 #D8D8D8,
                            stop: 0.5 #DDDDDD, stop: 1.0 #E1E1E1);
color:#fff;
}

QComboBox:on { /* shift the text when the popup opens */
padding-top: 3px;
padding-left: 4px;
color:#fff;
}

QComboBox::drop-down {
subcontrol-origin: padding;
subcontrol-position: top right;
width: 15px;

border-left-width: 1px;
border-left-color: darkgray;
border-left-style: solid; /* just a single line */
border-top-right-radius: 3px; /* same radius as the QComboBox */
border-bottom-right-radius: 3px;
color:#fff;
}

QComboBox::down-arrow {
image: url(/usr/share/icons/crystalsvg/16x16/actions/1downarrow.png);
color:#fff;
}

QComboBox::down-arrow:on { /* shift the arrow when popup is open */
top: 1px;
left: 1px;
color:#fff;
}