I've downloaded latest initializer: http://www.initializr.com/ to start a new project. As I have to support IE8 I quickly run through tests. And it turned out that when default theme is included:
<link rel="stylesheet" href="css/bootstrap-theme.min.css">
and I try to open sub-menu of Dropdown navigation menu, I see nothing: (Screenshot full size)
Actually you can see that dropdown menu is opening, but it's totally transparent. Is it common issue? Does it mean I have to give up on using default Bootstrap's theme?
I had the same Issue and removed the below line inside the class navbar-default of the theme CSS:
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffffff', endColorstr='#fff8f8f8', GradientType=0);