Simpler clearfix #2 http://nicolasgallagher.com/micro-clearfix-hack/

bootstrap-1.0.0.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: Fri Aug 19 19:51:25 PDT 2011
+ * Date: Fri Aug 19 20:19:39 PDT 2011
  */
 /* Reset.less
  * Props to Eric Meyer (meyerweb.com) for his CSS reset file. We're using an adapted version here	that cuts out some of the reset HTML elements we will never need here (i.e., dfn, samp, etc).
@@ -98,12 +98,12 @@ aside {
 .clearfix {
   zoom: 1;
 }
+.clearfix:before, .clearfix:after {
+  display: table;
+  content: "";
+}
 .clearfix:after {
-  display: block;
-  visibility: hidden;
-  height: 0;
   clear: both;
-  content: ".";
 }
 .center-block {
   display: block;
@@ -114,12 +114,12 @@ aside {
   margin: 0 auto;
   zoom: 1;
 }
+.container:before, .container:after {
+  display: table;
+  content: "";
+}
 .container:after {
-  display: block;
-  visibility: hidden;
-  height: 0;
   clear: both;
-  content: ".";
 }
 /*
  * Scaffolding
@@ -128,12 +128,12 @@ aside {
 .row {
   zoom: 1;
 }
+.row:before, .row:after {
+  display: table;
+  content: "";
+}
 .row:after {
-  display: block;
-  visibility: hidden;
-  height: 0;
   clear: both;
-  content: ".";
 }
 .row .span1 {
   float: left;
@@ -355,12 +355,12 @@ div.container-fluid {
   padding: 20px;
   zoom: 1;
 }
+div.container-fluid:before, div.container-fluid:after {
+  display: table;
+  content: "";
+}
 div.container-fluid:after {
-  display: block;
-  visibility: hidden;
-  height: 0;
   clear: both;
-  content: ".";
 }
 div.container-fluid div.sidebar {
   float: left;
@@ -1448,12 +1448,15 @@ ul.tabs, ul.pills {
   padding: 0;
   zoom: 1;
 }
+ul.tabs:before,
+ul.pills:before,
+ul.tabs:after,
+ul.pills:after {
+  display: table;
+  content: "";
+}
 ul.tabs:after, ul.pills:after {
-  display: block;
-  visibility: hidden;
-  height: 0;
   clear: both;
-  content: ".";
 }
 ul.tabs li, ul.pills li {
   display: inline;
@@ -1609,12 +1612,12 @@ div.modal .modal-footer {
   box-shadow: inset 0 1px 0 #ffffff;
   zoom: 1;
 }
+div.modal .modal-footer:before, div.modal .modal-footer:after {
+  display: table;
+  content: "";
+}
 div.modal .modal-footer:after {
-  display: block;
-  visibility: hidden;
-  height: 0;
   clear: both;
-  content: ".";
 }
 div.modal .modal-footer .btn {
   float: right;

bootstrap-1.0.0.min.css

@@ -4,10 +4,13 @@ table{border-collapse:collapse;border-spacing:0;}
 ol,ul{list-style:none;}
 q:before,q:after,blockquote:before,blockquote:after{content:"";}
 header,section,footer,article,aside{display:block;}
-.clearfix{zoom:1;}.clearfix:after{display:block;visibility:hidden;height:0;clear:both;content:".";}
+.clearfix{zoom:1;}.clearfix:before,.clearfix:after{display:table;content:"";}
+.clearfix:after{clear:both;}
 .center-block{display:block;margin:0 auto;}
-.container{width:940px;margin:0 auto;zoom:1;}.container:after{display:block;visibility:hidden;height:0;clear:both;content:".";}
-.row{zoom:1;}.row:after{display:block;visibility:hidden;height:0;clear:both;content:".";}
+.container{width:940px;margin:0 auto;zoom:1;}.container:before,.container:after{display:table;content:"";}
+.container:after{clear:both;}
+.row{zoom:1;}.row:before,.row:after{display:table;content:"";}
+.row:after{clear:both;}
 .row .span1{float:left;width:40px;margin-left:20px;}.row .span1:first-child{margin-left:0;}
 .row .span2{float:left;width:100px;margin-left:20px;}.row .span2:first-child{margin-left:0;}
 .row .span3{float:left;width:160px;margin-left:20px;}.row .span3:first-child{margin-left:0;}
@@ -39,7 +42,8 @@ header,section,footer,article,aside{display:block;}
 html,body{background-color:#fff;}
 body{margin:0;font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:13px;font-weight:normal;line-height:18px;color:#808080;text-rendering:optimizeLegibility;}
 div.container{width:940px;margin:0 auto;}
-div.container-fluid{padding:20px;zoom:1;}div.container-fluid:after{display:block;visibility:hidden;height:0;clear:both;content:".";}
+div.container-fluid{padding:20px;zoom:1;}div.container-fluid:before,div.container-fluid:after{display:table;content:"";}
+div.container-fluid:after{clear:both;}
 div.container-fluid div.sidebar{float:left;width:220px;}
 div.container-fluid div.content{min-width:700px;max-width:1180px;margin-left:240px;}
 a{color:#0069d6;text-decoration:none;line-height:inherit;}a:hover{color:#0050a3;text-decoration:underline;}
@@ -183,7 +187,8 @@ div.block-message.error{background:#f8dcda;border:1px solid #f4c8c5;}
 div.block-message.warning{background:#fff0c0;border:1px solid #ffe38d;}
 div.block-message.success{background:#dff1df;border:1px solid #bbe2bb;}
 div.block-message.info{background:#c7eefe;border:1px solid #ade6fe;}
-ul.tabs,ul.pills{margin:0 0 20px;padding:0;zoom:1;}ul.tabs:after,ul.pills:after{display:block;visibility:hidden;height:0;clear:both;content:".";}
+ul.tabs,ul.pills{margin:0 0 20px;padding:0;zoom:1;}ul.tabs:before,ul.pills:before,ul.tabs:after,ul.pills:after{display:table;content:"";}
+ul.tabs:after,ul.pills:after{clear:both;}
 ul.tabs li,ul.pills li{display:inline;}ul.tabs li a,ul.pills li a{float:left;width:auto;}
 ul.tabs{width:100%;border-bottom:1px solid #bfbfbf;}ul.tabs li a{margin-bottom:-1px;margin-right:2px;padding:0 15px;line-height:35px;-webkit-border-radius:3px 3px 0 0;-moz-border-radius:3px 3px 0 0;border-radius:3px 3px 0 0;}ul.tabs li a:hover{background-color:#e6e6e6;border-bottom:1px solid #bfbfbf;}
 ul.tabs li.active a{background-color:#fff;padding:0 14px;border:1px solid #ccc;border-bottom:0;color:#808080;}
@@ -197,7 +202,8 @@ div.well{background:#f5f5f5;margin-bottom:20px;padding:19px;min-height:20px;bord
 div.modal-backdrop{background-color:rgba(0, 0, 0, 0.5);position:fixed;top:0;left:0;right:0;bottom:0;z-index:1000;}
 div.modal{position:fixed;top:50%;left:50%;z-index:2000;width:560px;margin:-280px 0 0 -250px;background-color:#ffffff;border:1px solid rgba(0, 0, 0, 0.3);-webkit-border-radius:6px;-moz-border-radius:6px;border-radius:6px;-webkit-box-shadow:0 3px 7px rgba(0, 0, 0, 0.3);-moz-box-shadow:0 3px 7px rgba(0, 0, 0, 0.3);box-shadow:0 3px 7px rgba(0, 0, 0, 0.3);-webkit-background-clip:padding;-moz-background-clip:padding;background-clip:padding;}div.modal .modal-header{border-bottom:1px solid #eee;padding:5px 20px;}div.modal .modal-header a.close{position:absolute;right:10px;top:10px;color:#999;line-height:10px;font-size:18px;}
 div.modal .modal-body{padding:20px;}
-div.modal .modal-footer{background-color:#f5f5f5;padding:14px 20px 15px;border-top:1px solid #ddd;-webkit-border-radius:0 0 6px 6px;-moz-border-radius:0 0 6px 6px;border-radius:0 0 6px 6px;-webkit-box-shadow:inset 0 1px 0 #ffffff;-moz-box-shadow:inset 0 1px 0 #ffffff;box-shadow:inset 0 1px 0 #ffffff;zoom:1;}div.modal .modal-footer:after{display:block;visibility:hidden;height:0;clear:both;content:".";}
+div.modal .modal-footer{background-color:#f5f5f5;padding:14px 20px 15px;border-top:1px solid #ddd;-webkit-border-radius:0 0 6px 6px;-moz-border-radius:0 0 6px 6px;border-radius:0 0 6px 6px;-webkit-box-shadow:inset 0 1px 0 #ffffff;-moz-box-shadow:inset 0 1px 0 #ffffff;box-shadow:inset 0 1px 0 #ffffff;zoom:1;}div.modal .modal-footer:before,div.modal .modal-footer:after{display:table;content:"";}
+div.modal .modal-footer:after{clear:both;}
 div.modal .modal-footer .btn{float:right;margin-left:10px;}
 div.twipsy{display:block;position:absolute;visibility:visible;padding:5px;font-size:11px;z-index:1000;filter:alpha(opacity=80);-khtml-opacity:0.8;-moz-opacity:0.8;opacity:0.8;}div.twipsy.above .twipsy-arrow{bottom:0;left:50%;margin-left:-5px;border-left:5px solid transparent;border-right:5px solid transparent;border-top:5px solid #000000;}
 div.twipsy.left .twipsy-arrow{top:50%;right:0;margin-top:-5px;border-top:5px solid transparent;border-bottom:5px solid transparent;border-left:5px solid #000000;}

lib/preboot.less

@@ -54,15 +54,15 @@
 // MIXINS
 // ------
 
-// Clearfix for clearing floats like a boss
+// Clearfix for clearing floats like a boss h5bp.com/q
 .clearfix {
   zoom: 1;
+	&:before, &:after {
+    display: table;
+    content: "";
+	}
 	&:after {
-    display: block;
-    visibility: hidden;
-    height: 0;
     clear: both;
-    content: ".";
 	}
 }