Bootstrap dropdown menu don't work in IE8, 下拉選單在IE8出不來

解決方法:
加上filter:none !important;

.navbar-inverse .nav li.dropdown.open > .dropdown-toggle,
.navbar-inverse .nav li.dropdown.active > .dropdown-toggle,
.navbar-inverse .nav li.dropdown.open.active > .dropdown-toggle,
.nav,
.navbar,
.navbar-inverse .navbar-inner {
filter:none!important;
background-image: none;
}

參考網址:https://github.com/twbs/bootstrap/issues/6548