Theme Essentials

Main Colors

These colors are used throughout streamlit applications as of Feb 2, 2020.

NameHexUse
Primary#f63366Primary pink/magenta used for widgets throughout the app
Secondary#f0f2f6Background color of Sidebar
Black#262730Font Color
Yellow (Light)#fffd80Right side of top header decoration in app
White#ffffffBackground

View Colors

Streamlit Color Palette

Other Secondary Colors

These are defined in the variables.scss file described below, but are not heavily used within the streamlit applications.

NameHex
Red#ff2b2b
Yellow#faca2b
Blue#0068c9
Green#09ab3b

View Colors

Streamlit Secondary Palette

Fonts

Streamlit's default fonts are from the IBM Plex Collection

Text, including headers and markdown, is in IBM Plex Sans.

Code and data use IBM Plex Mono as the monospace font. This is used in markdown code blocks, the use of st.echo(), widget labels, st.json(), and rendered dataframes via st.dataframe and st.table.

Details

SCSS Variables

The essential aspects of streamlit's theme can be found in the variables.scss file in the frontend assets folder in the streamlit repository.

The essentials of the file are below (it's been slightly edited from the original file to remove extra information).

$gray-200: #f0f2f6;
$gray-600: #a3a8b4;
$gray-900: #262730;
$black: $gray-900;
$red: #ff2b2b;
$yellow: #faca2b;
$blue: #0068c9;
$green: #09ab3b;

$gray-lightest: $gray-200;
$yellow-light: #fffd80;

$primary: #f63366;
$secondary: $gray;

$font-family-sans-serif: "IBM Plex Sans", sans-serif;
$font-family-monospace: "IBM Plex Mono", monospace;

Bootstrap

Streamlit uses the Bootstrap framework behind the scenes. This means you can use bootstrap helper classes, for example img-fluid, if you're writing HTML within Markdown.

Generating New Palettes

If you want to generate some good looking color schemes that play off the existing streamlit colors, colormind.io and coolors.co are two helpful tools for creating new color schemes based off of a primary color. For generating color scales or palettes with more than 5 colors, the Chroma.js Color Palette Helper can't be beat.