optimize mac context a bit

Yuhang Zhao

2023-12-18 56c4ef0a85abb92a64bb90d86526f2218835e282

 examples/mainwindow/dark-style.qss

@@ -16,6 +16,7 @@
    border: none;
    color: #ECECEC;
    background-color: transparent;
    min-height: 28px;
}