how to alight and place ipywidgets

1from ipywidgets import widgets
2from IPython.display import Javascript, display
3
4align_kw = dict(
5    _css = (('.widget-label', 'min-width', '20ex'),),
6    margin = '0px 0px 5px 12px'
7)
8platform_ui = widgets.Dropdown(description = 'platform',options=['iPhone','iPad','Android'], **align_kw)
9event_type_ui = widgets.Text(value='open', description='Test Event', **align_kw)
10os_version_ui = widgets.Text(value='iOS9', description='Operating System', **align_kw)
11refresh_ui = widgets.Checkbox(description='Force Refresh', **align_kw)
12
13display(platform_ui,event_type_ui,os_version_ui,refresh_ui)
14