[Theme: Sight] Hover Menu Not Working

Hi,

I’m trying to figure out why hovering (mousing over) my menu (articles) no longer reveals the child pages. I have been tinkering with the CSS and can’t figure it out. Here is the site:

http://thinkhealthky.com

Here is the stylesheet navigation CSS:

.nav {border-top: 1px solid #BEBEBE;}
.dd {height: 26px;}
.dd li {float: left; display: block; border-left: 1px solid #BEBEBE; text-align: center; font-size: 19px; text-transform: uppercase;}
.dd li a {color: #676767; text-decoration: none; display: block; padding-top: 18px; margin: 0 20px; white-space: nowrap;}
.dd li a:hover {text-decoration: underline;}
.dd li ul {position: absolute; padding: 08px 0 10px; visibility: hidden; background: #676767; z-index: 100;}
.dd li ul li {float: none; border: none; font-size: 16px; text-align: left; margin: 05px 0; padding: 0 15px;}
.dd li ul li a {color: #fff; display: inline; margin: 0 !important; white-space: normal; padding-top: 0;}
.dd li.dd_hover {background: #676767;}
a.dd_hover:hover {text-decoration: none !important;}
.submenu a:hover {text-decoration: underline;}
.dd li.parent a {margin: 0 8px; padding-right: 12px; background: url("images/dd.png") 100% 24px no-repeat;}
.dd li.parent a.dd_hover {color: #fff; background: url("images/dd_hover.png") 100% 24px no-repeat; margin: 0 8px; padding-right: 12px; border-bottom: 1px solid #fff; padding-bottom: 10px;}

..

As you will see, mousing over the ‘articles’ menu does not reveal any subpages (child pages). However, if I change visibility: hidden to visibility: visible, the subpages become permanently visible. So it seems there is something wrong with how it is hiding the list of subpages. I apologize, I’m new to CSS, it’s probably a simple fix.

Thanks!