import random
import panel.widgets as pnw
import panel as pn
pn.extension()


def rcolor(): return "#%06x" % random.randint(0, 0xFFFFFF)


box = pn.FlexBox(*[pn.pane.HTML(str(i), styles=dict(background=rcolor()),
                 width=370, height=100, sizing_mode='fixed') for i in range(24)],
                 align_conten='start', styles={'background': 'black'}
                 )
box.servable()