Rounded border-top gradient problem

[Baldr76]

Hi,
I am using Qt 4.8.4 and I want to make a button, that has gradient on top and bottom borders only. The problem is, where I set the gradient for top or bottom, the gradient is on corner part of border also. My style scheet looks as below. What is wrong with it? How to set color for corner part exclusively?

@QPushButton, QLineEdit{
selection-background-color: darkgray;
background: black;
border-style: none;
border-radius: 16px;
padding: 16px;
color: rgb(253, 253, 253);
border-top: 5px solid qlineargradient(spread:reflect, x1:0.5, y1:0.5, x2:1, y2:0.5, stop:0 rgba(59, 59, 59, 255), stop:1 rgba(163, 163, 163, 255));
border-bottom: 5px solid qlineargradient(spread:reflect, x1:0.5, y1:0.5, x2:1, y2:0.5, stop:0 rgba(59, 59, 59, 255), stop:1 rgba(163, 163, 163, 255));
border-left: 5px solid rgb(163, 163, 163);
border-right: 5px solid rgb(163, 163, 163);
}@

Thanks in advance for a help.