don't use negative margin - use first child to set to 0

bootstrap.css

@@ -6,7 +6,7 @@
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Designed and built with all the love in the world @twitter by @mdo and @fat.
- * Date: Sun Jan 22 20:06:46 PST 2012
+ * Date: Sun Jan 22 20:11:39 PST 2012
  */
 html, body {
   margin: 0;
@@ -238,7 +238,6 @@ a:hover {
   text-decoration: underline;
 }
 .row {
-  margin-left: -20px;
   *zoom: 1;
 }
 .row:before, .row:after {
@@ -248,6 +247,9 @@ a:hover {
 .row:after {
   clear: both;
 }
+[class*="span"]:first-child {
+  margin-left: 0;
+}
 [class*="span"] {
   float: left;
   margin-left: 20px;

bootstrap.min.css

@@ -32,8 +32,9 @@ body{margin:0;font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:
 .sidebar-right .fluid-sidebar{float:right;margin-right:-240px;}
 .fluid-content{float:left;width:100%;}
 a{font-weight:inherit;line-height:inherit;color:#0088cc;text-decoration:none;}a:hover{color:#005580;text-decoration:underline;}
-.row{margin-left:-20px;*zoom:1;}.row:before,.row:after{display:table;content:"";}
+.row{*zoom:1;}.row:before,.row:after{display:table;content:"";}
 .row:after{clear:both;}
+[class*="span"]:first-child{margin-left:0;}
 [class*="span"]{float:left;margin-left:20px;}
 .span1{width:60px;}
 .span2{width:140px;}

lib/scaffolding.less

@@ -75,11 +75,15 @@ a {
 // -----------
 // To customize the grid system, bring up the variables.less file and change the column count, size, and gutter there
 .row {
-  margin-left: -@gridGutterWidth;
   .clearfix();
 }
 
-// Find all .span# classes within .row and give them the necessary properties for grid columns (supported by all browsers back to IE7)
+[class*="span"]:first-child{
+  margin-left: 0;
+}
+
+// Find all .span# classes within .row and give them the necessary properties for grid columns 
+// (supported by all browsers back to IE7)
 // Credit to @dhg for the idea
 [class*="span"] {
   .gridColumn();