Dimmer switch

The forums are run by a company called Jive, and I don't think they have different themes.

If you're familiar with HTML and CSS you can use a CSS injector (plugin/extension in your browser) to change colors, fonts, etc. I use Control Freak for Opera.

Here's the CSS I use for this site - feel free to use it and modify it.

There may be some redundant code in there, but it works.

body {font-family: 'Source Sans Pro' !important;}
.jive-table-cell-subject a:link {color: black !important;}
.jive-table-cell-author,  .jive-table-cell-subject, .jive-table-cell-modified, .jive-table-cell-views, .jive-table-cell-replies {font-size: 84% !important;}
.jive-code {font-size: 84% !important;}
.jive-thread-reply-body-container {background-color: #f4f4f4 !important;}
.j-td-title, .j-td-actions, .j-td-icon {padding: 4px !important; border-bottom: 1px solid #d5d5d5 !important;}
.j-td-title a {color: black !important; font-family: 'Source Sans Pro' !important; font-size: 100% !important;}
.j-td-title a:link {font-family: Corbel !important; color:#2b2b2b !important; font-weight:300 !important;}
.j-td-title a:visited {color: #787878 !important;}
#j-satNav-wrap {position:fixed !important; top:8px !important; right:230px !important; z-index:1000 !important;}
.j-td-replies {font-weight: bold !important;}
.j-td-bookmarks {display:none !important;}
.j-td-likes {display:none !important;}
.j-td-actions {display:none !important;}
.j-column-wrap-1, .js-browse-item, .j-column {background-color: rgba(240,240,240,1) !important;}
.j-td-replies {color:black !important; font-weight:800 !important;}

The result looks like this: