change .span* inputs to use content-sizing: border-box; to make them behave as block level elements

docs/assets/css/bootstrap-responsive.css

@@ -7,6 +7,33 @@
     display: block;
     line-height: 18px;
   }
+  input[class*="span"],
+  select[class*="span"],
+  textarea[class*="span"],
+  .uneditable-input {
+    display: block;
+    width: 100%;
+    height: 28px;
+    /* Make inputs at least the height of their button counterpart */
+  
+    /* Makes inputs behave like true block-level elements */
+  
+    -webkit-box-sizing: border-box;
+    /* Older Webkit */
+  
+    -moz-box-sizing: border-box;
+    /* Older FF */
+  
+    -ms-box-sizing: border-box;
+    /* IE8 */
+  
+    box-sizing: border-box;
+    /* CSS3 spec*/
+  
+  }
+  .input-prepend input[class*="span"], .input-append input[class*="span"] {
+    width: auto;
+  }
   input[type="checkbox"], input[type="radio"] {
     border: 1px solid #ccc;
   }