fix popup positioning

build/css/tempusdominus-bootstrap-3-standalone.css

@@ -1,3 +1,9 @@
+/*@preserve
+ * Tempus Dominus Bootstrap3 v5.0.0-alpha10 (https://tempusdominus.github.io/bootstrap-3/)
+ * Copyright 2016-2020 Jonathan Peterson
+ * Licensed under MIT (https://github.com/tempusdominus/bootstrap-3/blob/master/LICENSE)
+ */
+
 /*@preserve
  * Tempus Dominus Bootstrap3 v5.0.0-alpha10 (https://tempusdominus.github.io/bootstrap-3/)
  * Copyright 2016-2018 Jonathan Peterson

build/css/tempusdominus-bootstrap-3.css

@@ -1,6 +1,6 @@
 /*@preserve
  * Tempus Dominus Bootstrap3 v5.0.0-alpha10 (https://tempusdominus.github.io/bootstrap-3/)
- * Copyright 2016-2018 Jonathan Peterson
+ * Copyright 2016-2020 Jonathan Peterson
  * Licensed under MIT (https://github.com/tempusdominus/bootstrap-3/blob/master/LICENSE)
  */
 
@@ -274,7 +274,7 @@
   width: 54px;
 }
 .bootstrap-datetimepicker-widget table td.cw {
-  font-size: .8em;
+  font-size: 0.8em;
   height: 20px;
   line-height: 20px;
   color: #777777;

build/js/tempusdominus-bootstrap-3.js

@@ -1,6 +1,6 @@
 /*@preserve
  * Tempus Dominus Bootstrap3 v5.0.0-alpha10 (https://tempusdominus.github.io/bootstrap-3/)
- * Copyright 2016-2018 Jonathan Peterson
+ * Copyright 2016-2020 Jonathan Peterson
  * Licensed under MIT (https://github.com/tempusdominus/bootstrap-3/blob/master/LICENSE)
  */
 
@@ -410,6 +410,11 @@ var DateTimePicker = function ($, moment) {
                 if (!this._options.allowMultidate || this._dates.length === 1) {
                     this.unset = true;
                     this._dates = [];
+
+                    // https://github.com/tempusdominus/bootstrap-4/issues/34#issuecomment-414392321
+                    this._dates[0] = this.getMoment();
+                    this._viewDate[0] = this.getMoment().clone();
+
                     this._datesFormatted = [];
                 } else {
                     outpValue = this._element.data('date') + ',';
@@ -1886,15 +1891,15 @@ var TempusDominusBootstrap3 = function ($) {
                 self.widget.removeClass('pull-right');
             }
 
-            // find the first parent element that has a static css positioning
-            if (parent.css('position') !== 'static') {
+            // find the first parent element that has a relative css positioning
+            if (parent.css('position') !== 'relative') {
                 parent = parent.parents().filter(function () {
-                    return $(this).css('position') === 'static';
+                    return $(this).css('position') === 'relative';
                 }).first();
             }
 
             if (parent.length === 0) {
-                throw new Error('datetimepicker component should be placed within a static positioned container');
+                throw new Error('datetimepicker component should be placed within a relative positioned container');
             }
 
             self.widget.css({