Python dash Div 整页背景图片

Question

Sorry i'm very new to dash, css, html coding.

i'm using Dash on Python and i would like a simple full page background with an image.

i'm using this CSS: https://codepen.io/chriddyp/pen/bWLwgP.css

i tried to use different CSS ( https://necolas.github.io/normalize.css/8.0.1/normalize.css ) beacuse i read it was a margin problem but it didn't work

i've read a lot of discussion about this issue but i wasn't able to fix it for my purposes

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app       = dash.Dash(__name__,
                      external_stylesheets = external_stylesheets)


app.title = "Q"


colors = {'background': '#ffffff',
          'bg_home': '#666666',
          'text': '#ffa500',
          'background_plot': '#cccccc',
          'text_plot': '#000000'}

app.config['suppress_callback_exceptions']=True
image   = 'url(https://c.wallhere.com/photos/a1/fc/1920x1080_px_Albert_Einstein_Formula_mathematics_physics_science_Special_Relativity-549404.jpg!d)'

app.layout = html.Div(

                className='row',
                  style={
                          'verticalAlign':'middle',
                          'textAlign': 'center',
                          'background-image':image,


                            },

                  children= [
                           html.Div(
                                   id='Username',
                                    style={'textAlign': 'center',
                                           'verticalAlign':'middle',
                                           },
                                    children= [         
                                            html.H3('Login',
                                                        style={'textAlign': 'center',
                                                           'color':'orange',
                                                           'fontWeight': 'bold',
                                                               },                                                       
                                                    ),
                                            html.Div(             
                                                    className='row', 
                                                    children=[
                                                         dcc.Input(id = 'user',
                                                                   style={'margin-top':20},
                                                                  type='text',
                                                                  placeholder='Username'
                                                                  )
                                                             ]
                                                     ),
                                            html.Div(className='row', 
                                                     children=[
                                                        dcc.Input(id = 'psw',
                                                                  style={'margin-top':20},
                                                                  type='text',
                                                                  placeholder='Password'
                                                                  )
                                                                ]
                                                     ),
                                            html.Div(className='row',  
                                                     children=[
                                                         html.Button('Login',
                                                                    id='log',
                                                                    style={'background-color':'white',
                                                                            'color':'black',
                                                                            'margin-top': 20,
                                                                            'textAlign':'right'},
                                                                   ),
                                                             ]
                                                     )


                                              ])


                           ]
                    )

if __name__ == '__main__':
    app.run_server(debug=True,host='0.0.0.0',port=8050)

i'm not gettin error but i just get 1/3 (more or less) of the page with background image and login Div, the rest of the page completely white.

I just would like a full page with background image and login in the center

Thank you all

Answer 1

In css body tag defines the document's whole body and the div is a part of it, there are two ways to get this working.

1. Make the div to cover the entire page and set the image to the div

Refer here: Making a div that covers the entire page

Modified bit of code,

className='row',
style={
  'verticalAlign':'middle',
  'textAlign': 'center',
  'background-image':image,
  'position':'fixed',
  'width':'100%',
  'height':'100%',
  'top':'0px',
  'left':'0px',
  'z-index':'1000'
},

2. Modify the body tag in the external_stylesheet to have the property background-image ,

body {
   'background-image' : url(url!d);
}

Answer 2

There are 2 ways to get this done:

Note: Is is a good practice to create a folder 'assets' in the program's root directory, and place your image inside it.

Method-1:

app.layout = html.Div([ ...fill your children here... ],
   style={'background-image': 'url(/assets/image.jpg)',
          'background-size': '100%',
          'position': 'fixed',
          'width': '100%',
          'height': '100%'
          })

Method-2:

app.layout = html.Div([ ...fill your children here... ],
   style={'background-image': 'url(/assets/image.jpg)',
          'background-size': '100%',
          'width': '100vw',
          'height': '100vh'
          })