My menu's background is white, and so is my link text when I hover over it. How to fix?

Open up Themes > Template Editor > bootstrap.css

Around line 3869, comment out the line of code in bold below, but putting /* and */ around it, like below:

.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 {
  background-color: #111111;
  /*color: #ffffff; */
}

To be clear:  above, you'll see asterisks and slashes to comment out that line of code. 

/* this code in between will be commented out */

So you need to comment out out the line of code as above in bold/underline.

This was an earlier oversight in some of the earlier versions of our theme.  That's how to fix it in a jiffy!

Done.