UX: improves date-time-input on mobile (#9291)

app/assets/javascripts/discourse/components/date-time-input.js

@@ -32,6 +32,7 @@ export default Component.extend({
 
     onChangeDate(date) {
       if (this.onChange) {
+        date = new Date(this.date);
         const year = date.getFullYear();
         const month = date.getMonth();
         const day = date.getDate();

app/assets/stylesheets/common/components/date-input.scss

@@ -1,4 +1,7 @@
 .d-date-input {
+  display: flex;
+  flex: 1;
+
   .date-picker {
     margin: 0;
     text-align: left;

app/assets/stylesheets/common/components/date-time-input.scss

@@ -2,14 +2,16 @@
   display: flex;
   align-items: center;
   border: 1px solid $primary-low;
-  width: 258px;
   box-sizing: border-box;
   position: relative;
   flex: 1;
-  justify-content: space-between;
 
   .date-picker,
   .fields {
     border: 0;
   }
+
+  .d-date-time-input {
+    margin-left: auto;
+  }
 }