QScrollBar page area has undesired pattern

[pixaeiro]

Hello,

I'm customizing the theme of my application with QSS and the QScrollBar page area is showing an undesired checkboard pattern:

QScrollBar.png

The pattern is a checkboard of the desired background color and white. I have no idea where this white is coming from!

This is the shortest QScrollBar qss code that reproduced the issue:

QScrollBar
{
    background-color: rgb(65,65,65);
    border: 2px solid rgb(50,50,50);
}

QScrollBar
{
    background-color: rgb(65,65,65);
    border: 2px solid rgb(50,50,50);
}

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Does anybody know what is the QSS property for the white color? Or for turning off the checkboard pattern?

Thank you!