Bulma Functions

Last Updated : 23 Jul, 2025

Bulma is an Open source CSS framework which is developed by Jeremy Thomas. This framework is basically based on the CSS Flexbox property. It is highly responsive and it helps in minimizing the use of media queries for responsive behaviour.

In this article, we’ll learn about Bulma Functions. The Bulma Functions provide custom Sass functions and a few utility functions that help users to find the related colors dynamically and to calculate the useful values.

1. The Bulma Functions to find the related colors dynamically:

findLightColor() function: This function is used to provide the lighter version of the input color.
findDarkColor() function: This function is used to provide the darker version of the input color.
findColorInvert() function: This function is used to provide a readable shade for the text when the input color is used as the background or vice-versa

2. The Bulma Functions to calculate the useful value:

powerNumber() function: This function is used to calculate the value of a number exposed to another one.
colorLuminance() function: This function is used to check if color is dark or light.

Setup: After Bulma's initial setup, do the following:

Step 1: Create a package.json file for your project.

Command: npm init

The package.json will be created.

{
 "name": "test",
 "version": "1.0.0",
 "description": "",
 "main": "index.js",
 "scripts": {
 "test": "echo \"Error: no test specified\" && exit 1"
 },
 "author": "",
 "license": "ISC"
}

Step 2: Now install dev dependencies

Command1: npm install node-sass --save-dev
Command2: npm install bulma --save-dev

Step 3: Now create a customized sass file - gfgstyles.scss.

@charset "utf-8";
// path to bulma.sass can be find from 
// node_modules/bulma install from Step 2
@import "/path/to/bulma/bulma.sass";

Now Update the package.json file with the following:

"main": "/path/to/gfgstyles.scss",
"scripts": {
"css-build": "node-sass --omit-source-map-url /path/to/gfgstyles.scss css/gfgstyles.css",
"css-watch": "npm run css-build -- --watch",
"start": "npm run css-watch"
}

Step 4: Run the below command to generate css/gfgstyles.css from sass/gfgstyles.scss which can be used in HTML CSS styling.

npm run css-build

Note: Each and every time when gfgstyles.scss is modified, you need to run Step 4.

Example 1: The following code demonstrates a function to find the related colors dynamically - findColorInvert() function.

Output: Using built-in findColorInvert() function usage

👁 Image

Now update the gfgstyles.scss with the following:

@charset "utf-8";

// Update Bulma's global invert variables
$info-invert: findColorInvert(light);
$success-invert: findColorInvert(light);
$warning-invert: findColorInvert(light);
$danger-invert: findColorInvert(light);
$light-invert: findColorInvert(light);
$dark-invert: findColorInvert(light);

@import "../node_modules/bulma/bulma.sass";

and run the below command:

npm run css-build

Then Re-run the HTML code. The text color in the button changes from #fff to rgba(#000, 0.7).

Output: After the changes

👁 Image

Example 2: The following code demonstrates a function to calculate the useful value - colorLuminance() function.

Output: Using built-in function usage

👁 Image

Now update the gfgstyles.scss with the following:

@charset "utf-8";
@import "../node_modules/bulma/sass/utilities/functions.sass";

// Update Bulma function
@function findColor($color) {
 @if (colorLuminance($color) < 0.55) {
 @return purple;
 }
 @else {
 @return green;
 }
}

$info-invert: findColor(info);
$success-invert: findColor(success);
$warning-invert: findColor(warning);
$danger-invert: findColor(danger);
$light-invert: findColor(light);
$dark-invert: findColor(dark);

@import "../node_modules/bulma/bulma.sass";

and run the below command: