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Customizing AstroPaper theme color schemes

September 25, 2022 | 03:20 PM

This post will explain how you can enable/disable light & dark mode for the website. Moreover, you’ll learn how you can customize color schemes of the entire website.

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Enable/disable light & dark mode

AstroPaper theme will include light and dark mode by default. In other words, there will be two color schemes_ one for light mode and another for dark mode. This default behavior can be disabled in SITE configuration object of the src/config.ts file.

// file: src/config.ts
export const SITE = {
  website: "",
  author: "Sat Naing",
  desc: "A minimal, responsive and SEO-friendly Astro blog theme.",
  title: "AstroPaper",
  ogImage: "og-default.png",
  lightAndDarkMode: true, // true by default
  postPerPage: 3,

To disable light & dark mode set SITE.lightAndDarkMode to false.

Choose primary color scheme

By default, if we disable SITE.lightAndDarkMode, we will only get system’s prefers-color-scheme.

Thus, to choose primary color scheme instead of prefers-color-scheme, we have to set color scheme in the primaryColorScheme variable inside src/layouts/Layout.astro.

<!-- src/layouts/Layout.astro -->
<script is:inline>
  const primaryColorScheme = "none"; // "light" | "dark" | "none"

  const darkModeMediaQuery = window.matchMedia(
    "(prefers-color-scheme: dark)"

  // Get theme data from local storage
  const currentTheme = localStorage.getItem("theme");

  // some more script codes ...

The primaryColorScheme variable can hold three values_ "light", "dark", "none".

Why 'primaryColorScheme' is not inside config.ts?

To avoid color flickering on page reload, we have to place some JavaScript codes in the inline script tag. It solves the problem of flickering, but as a trade-off, we cannot use ESM imports anymore.

Click here to know more about Astro’s inline script.

Customize color schemes

Both light & dark color schemes of AstroPaper theme can be customized. You can do this in src/styles/base.css file.

/* file: src/styles/base.css */
@tailwind base;
@tailwind components;
@tailwind utilities;

@layer base {
  :root {
    --color-fill: 251, 254, 251;
    --color-text-base: 40, 39, 40;
    --color-accent: 0, 108, 172;
    --color-card: 230, 230, 230;
    --color-card-muted: 205, 205, 205;
    --color-border: 236, 233, 233;
  .theme-dark {
    --color-fill: 47, 55, 65;
    --color-text-base: 230, 230, 230;
    --color-accent: 26, 217, 217;
    --color-card: 63, 75, 90;
    --color-card-muted: 89, 107, 129;
    --color-border: 59, 70, 85;
  /* other styles */

In AstroPaper theme, :root is the light color scheme and .theme-dark is the dark color scheme. If you want to customize your custom color scheme, it is recommended that you set light color scheme inside :root and dark color scheme inside .theme-dark.

Colors are declared in CSS custom property (CSS Variable) notation. Color property values are written in rgb values. (Note: instead of rgb(40, 39, 40), only specify 40, 39, 40)

Here is the detail explaination of color properties.

Color PropertyDefinition & Usage
--color-fillPrimary color of the website. Usually the main background.
--color-text-baseSecondary color of the website. Usually the text color.
--color-accentAccent color of the website. Link color, hover color etc.
--color-cardCard, scrollbar and code background color.
--color-card-mutedCard and scrollbar background color for hover state etc.
--color-borderBorder color. Especially used in horizontal row (hr)

Here is an example of changing the light color scheme.

@layer base {
  /* lobster color scheme */
  :root {
    --color-fill: 246, 238, 225;
    --color-text-base: 1, 44, 86;
    --color-accent: 225, 74, 57;
    --color-card: 220, 152, 145;
    --color-card-muted: 233, 119, 106;
    --color-border: 220, 152, 145;