@
button->setStyleString("QPushButton{" +
"padding: " + QString::number(width/3) + "px;" +
"border-radius: " + QString::number(radius/5) + "px;" +
"background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, " +
"stop: 0 #3d94f6, stop: 1 #29569e);" +
"background: transparent" +
"color: white;" +
"font-family: arial;" +
"font-size: " + QString::number(fontSize) + "px;" +
"font-weight: bold" +
"}" +
"QPushButton:hover{" +
"border: 2px solid black;" +
"border-radius: " + QString::number(radius/4) + "px;" +
"background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, " +
"stop: 0 #29569e, stop: 1 #3d94f6);" +
"}"+
"QPushButton:checked{" +
"border: 3px solid black;" +
"border-radius: " + QString::number(radius/3) + "px;" +
"background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, " +
"stop: 0 #29569e, stop: 1 #3d94f6);" +
"}");

@

I tried that two methods:

@

QPushButton{
"background:transparent;"
...
...
}

@

and also

@

button->setAttribute(Qt::WA_TranslucentBackground);

@

but it didn't work (nothing changed)

To fix the gray background, you can make the background of the button transparent (but not the frame with the rounded edges and text).

So you can add to your stylesheet:

@
QPushButton {
"background:transparent;"
...
...
}
@

or you can set the background to translucent:

@
button->setAttribute(Qt::WA_TranslucentBackground);
@