Apply CSS class to Pandas DataFrame using to_html

Pandas’ to_html simply outputs a large string containing HTML table markup. The classes argument is a convenience handler to give the <table> a class attribute that will be referenced in a previously created CSS document that styles it. Therefore, incorporate to_html into a wider HTML document build that references an external CSS.

Interestingly, to_html adds dual classes <table class="dataframe mystyle"> which can be referenced in CSS individually, .dataframe {...} .mystyle{...}, or together .dataframe.mystyle {...}. Below demonstrates with random data.


import pandas as pd
import numpy as np

pd.set_option('display.width', 1000)
pd.set_option('colheader_justify', 'center')

demo_df = pd.DataFrame({'date': np.random.choice(pd.date_range('2018-01-01', '2018-06-18', freq='D'), 50),
                        'analysis_tool': np.random.choice(['pandas', 'r', 'julia', 'sas', 'stata', 'spss'],50),              
                        'database': np.random.choice(['postgres', 'mysql', 'sqlite', 'oracle', 'sql server', 'db2'],50), 
                        'os': np.random.choice(['windows 10', 'ubuntu', 'mac os', 'android', 'ios', 'windows 7', 'debian'],50), 
                        'num1': np.random.randn(50)*100,
                        'num2': np.random.uniform(0,1,50),                   
                        'num3': np.random.randint(100, size=50),
                        'bool': np.random.choice([True, False], 50)
                        columns=['date', 'analysis_tool', 'num1', 'database', 'num2', 'os', 'num3', 'bool']

#      date    analysis_tool     num1      database     num2        os      num3  bool 
# 0 2018-04-21     pandas     153.474246       mysql  0.658533         ios   74    True
# 1 2018-04-13        sas     199.461669      sqlite  0.656985   windows 7   11   False
# 2 2018-06-09      stata      12.918608      oracle  0.495707     android   25   False
# 3 2018-04-24       spss      88.562111  sql server  0.113580   windows 7   42   False
# 4 2018-05-05       spss     110.231277      oracle  0.660977  windows 10   76    True
# 5 2018-04-05        sas     -68.140295  sql server  0.346894  windows 10    0    True
# 6 2018-05-07      julia      12.874660    postgres  0.195217         ios   79    True
# 7 2018-01-22          r     189.410928       mysql  0.234815  windows 10   56   False
# 8 2018-01-12     pandas    -111.412564  sql server  0.580253      debian   30   False
# 9 2018-04-12          r      38.963967    postgres  0.266604   windows 7   46   False

CSS (save as df_style.css)

/* includes alternating gray and white with on-hover color */

.mystyle {
    font-size: 11pt; 
    font-family: Arial;
    border-collapse: collapse; 
    border: 1px solid silver;


.mystyle td, th {
    padding: 5px;

.mystyle tr:nth-child(even) {
    background: #E0E0E0;

.mystyle tr:hover {
    background: silver;
    cursor: pointer;


pd.set_option('colheader_justify', 'center')   # FOR TABLE <th>

html_string = '''
  <head><title>HTML Pandas Dataframe with CSS</title></head>
  <link rel="stylesheet" type="text/css" href=""/>

with open('myhtml.html', 'w') as f:


HTML (references df_style.css, assumed in same directory; see class argument in table)

  <head><title>HTML Pandas Dataframe with CSS</title></head>
  <link rel="stylesheet" type="text/css" href=""/>
    <table border="1" class="dataframe mystyle">
    <tr style="text-align: center;">
      <td>windows 7</td>
      <td>sql server</td>
      <td>windows 7</td>
      <td>windows 10</td>

HTML Output

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