How to add an external css file

Hi there I am working on dash in (pycharm) , I had created a new file in pycharm as assets.css and I need to link this file into my dash file , I don’t know how to link this file can anyone help me out with this
below is my code

import dash
import dash_html_components as html
import dash_core_components as dcc

app = dash.Dash(name ,external_scripts=externalstyle)
app.css.config.serve_locally = True
app.scripts.config.serve_locally = True
external_style =[‘C:/Users/PycharmProjects/dash/assets/style.css’]
app = dash.Dash(name ,external_scripts=external_style)

app.layout = html.Div([
# header

html.Div(
[

html.Span(html.H2(html.B(“Al Rajhi Bank -(Transaction Data)”)) ,className=‘app-header’ ),

html.Div(
html.Img(src=“https://img.icons8.com/wired/50/e67e22/museum.png” ,height=“100%”) , style={“float”: “right”, “height”: “100%”,“display”:'inline-block '}

)

]
)

]
)

if name==‘main’:
app.run_server(debug=True)

See CSS documentation here: https://dash.plot.ly/external-resources