悬停时的背景是因为此代码来自 bootstrap.css 第 6 行。filter 属性用于在 ie.in 第 106 行 app.css 中应用渐变,所有属性都被覆盖但不过滤,因此在即有蓝色背景.
.dropdown-menu li > a:hover, .dropdown-menu li > a:focus, .dropdown-submenu:hover > a {
color: white;
text-decoration: none;
background-color: #08C;
background-color: #0081C2;
background-image: -moz-linear-gradient(top,#08C,#0077B3);
background-image: -webkit-gradient(linear,0 0,0 100%,from(#08C),to(#0077B3));
background-image: -webkit-linear-gradient(top,#08C,#0077B3);
background-image: -o-linear-gradient(top,#08C,#0077B3);
background-image: linear-gradient(to bottom,#08C,#0077B3);
background-repeat: repeat-x;
filter: progid:dximagetransform.microsoft.gradient(startColorstr='#ff0088cc',endColorstr='#ff0077b3',GradientType=0);
}