I am confused as to how to layout controls in `dash`. How do I put the `dropdown` and the `datepicker` on the same row side-by-side?

```
html.Div(
      [
        html.Div(
          [
            dcc.Dropdown(id='dropdown',
              options=[{'label': i, 'value': i} for i in all_options],
              multi=False,
               placeholder='Select Symbol...',
            ),
            dcc.DatePickerSingle(
              id='my-date-picker-single',
              min_date_allowed=today,
              max_date_allowed=today,
              initial_visible_month=today,
              date=today)
          ],
          className='row'
       ),
     ]
    ),

```