Bootstrap 導航欄 下拉 寬度撐開滿屏

--------移動到下拉顯示-------------------------------
nav .dropdown:hover .dropdown-menu {
    display:block; width: 100%;  text-align: center; left:0; right:0;
    background-color: RGBA(0, 127, 216, 0.8);


}
nav .dropdown:hover { position: static; }

------------------------------點擊下拉顯示-----------------------------------------

.dropdown.open { position: static; }
.dropdown.open .dropdown-menu {display:block; width: 100%; text-align: center; left:0; right:0; }

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