Fixes #6954: properly reset grid classes within tables

docs/assets/css/bootstrap.css

@@ -975,11 +975,15 @@ th {
   background-color: #f5f5f5;
 }
 
-table td[class*="span"],
-table th[class*="span"] {
+table col[class^="span"] {
+  display: table-column;
+  float: none;
+}
+
+table td[class^="span"],
+table th[class^="span"] {
   display: table-cell;
   float: none;
-  margin-left: 0;
 }
 
 .table tbody tr.success > td {

less/tables.less

@@ -177,12 +177,15 @@ th {
 // TABLE CELL SIZING
 // -----------------
 
-// Reset default grid behavior
-table td[class*="span"],
-table th[class*="span"] {
+// Reset default table behavior
+table col[class^="span"] {
+  float: none;
+  display: table-column;
+}
+table td[class^="span"],
+table th[class^="span"] {
+  float: none;
   display: table-cell;
-  float: none; // undo default grid column styles
-  margin-left: 0; // undo default grid column styles
 }
 
 // TABLE BACKGROUNDS