Style not completly applied in Customization notebook example

[xavArtley]

In the user guide https://panel.pyviz.org/user_guide/Customization.html

following the definition of the css the widget-box should be like this

However the border css is not applied because overrided by the bokeh one:

The solution is to add !important to the css

css = '''
.widget-box {
  background: #f0f0f0;
  border-radius: 5px;
  border: 1px black solid !important;
}
'''