Fix #2085

Example: http://jsfiddle.net/djhvscf/4r6g4cfu/220/

src/bootstrap-table.js

@@ -2102,7 +2102,8 @@
             that.$header_.find(sprintf('th[data-field="%s"]', $(this).data('field'))).data($(this).data());
         });
 
-        var visibleFields = this.getVisibleFields();
+        var visibleFields = this.getVisibleFields(),
+            ths = this.$header_.find('th');
 
         this.$body.find('>tr:first-child:not(.no-records-found) > *').each(function (i) {
             var $this = $(this),
@@ -2115,8 +2116,12 @@
                 index = i - 1;
             }
 
-            that.$header_.find(sprintf('th[data-field="%s"]', visibleFields[index]))
-                .find('.fht-cell').width($this.innerWidth());
+            var th = that.$header_.find(sprintf('th[data-field="%s"]', visibleFields[index]));
+            if (th.length > 1) {
+                th = $(ths[$this[0].cellIndex]);
+            }
+
+            th.find('.fht-cell').width($this.innerWidth());
         });
         // horizontal scroll event
         // TODO: it's probably better improving the layout than binding to scroll event