BuddyPress.org

Try this which should work:

/*
Theme Name: TSS
Theme URI: http://www.thescratchingshed.com/themes/tss/
Description: TSS custom
Version: 1.0
Author: TSS
Author URI: http://www.thescratchingshed.com/
Template: bp-default
Tags: buddypress, two-column, blue, white
*/

/* Inherit the default theme styles */

@import url( ../../plugins/buddypress/bp-themes/bp-default/_inc/css/default.css );

/* Inherit the default theme adminbar styles */

@import url( ../../plugins/buddypress/bp-themes/bp-default/_inc/css/adminbar.css );

/* Begin custom styles

---

*/
/* change primary sidebar width to 300px */
div#content .padder {margin-right:300px;}
div#sidebar {width:300px;margin-left:-301px;}