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Customizing AstroPaper theme color schemes

Published: at 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: "astropaper-og.jpg",
  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 public/toggle-theme.js.

/* file: public/toggle-theme.js */
const primaryColorScheme = ""; // "light" | "dark"

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

// other codes etc...

The primaryColorScheme variable can hold two values_ "light", "dark". You can leave the empty string (default) if you don’t want to specify the primary color scheme.

Why 'primaryColorScheme' is not inside config.ts?

To avoid color flickering on page reload, we have to place the toggle-switch JavaScript codes as early as possible when the page loads. 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 is: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 {
  html[data-theme="light"] {
    --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;
  html[data-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 and html[data-theme="light"] selectors are used as the light color scheme and html[data-theme="dark"] is used the dark color scheme. If you want to customize your custom color scheme, you have to specify your light color scheme inside :root,html[data-theme="light"] and dark color scheme inside html[data-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 explanation 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 (like this).
--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 */
  html[data-theme="light"] {
    --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;

Check out some predefined color schemes AstroPaper has already crafted for you.