Rectangle border with a partial transparent color looks weird

import QtQuick 2.0

Rectangle {
    width: 360
    height: 360


    Rectangle {
        x: 42
        y: 43
        width: 257
        height: 272
        color: "#d3d348"
        radius: 1
        border.color: "#6421dbc6"
        border.width: 25
        opacity: 1
    }

}