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Tweaking Bootstrap's Sass

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Now that we finally have Bootstrap's Sass working, we can celebrate! Inside _bootstrap.scss, the first thing it imports is an _variables.scss file. I'll hold Command and click to open that.

Awesome! This holds a bunch of variables that are used throughout the rest of the Sass files. Yep, this means we can override these to control colors and many other things.

Copy the $brand-primary variable line. Then, at the top of our main.scss file, before we import Bootstrap, override that variable. Make sure to remove the default.

This variable is used to color some buttons and a lot of other things. Let's make it a little lighter: change the 6.5 to 2.5. It's not important, but the new color should be #3885C7:

$brand-primary: darken(#428bca, 2.5%); // #3885c7
... lines 2 - 82

Back in the browser, inspect the "I Lifted It!" button. Yep! The current color is #337AB7. Now, refresh! Check it out. Yes! It's the slightly lighter #3885C7.

So this is really the reason why you might want to import Bootstrap as Sass, instead of CSS.

Importing Only Parts of Bootstrap

Let's do one more thing! The _bootstrap.scss file imports every part of Bootstrap. But what if you don't need every part of Bootstrap? For example, we are not using the glyphicons. Importing that CSS is wasteful!

Let's fix this! Copy the entire contents of _bootstrap.scss. Then, in our css/ directory, create a new _bootstrap.scss file and paste that here.

As soon as we do that... all the paths are broken! Yea, that makes sense: we're in a different directory. No problem, I'll copy "bootstrap and do a "Find and Replace" to replace this with "~bootstrap-sass/assets/stylesheets/bootstrap. Replace everything!

// Core variables and mixins
@import "~bootstrap-sass/assets/stylesheets/bootstrap/variables";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/mixins";
// Reset and dependencies
@import "~bootstrap-sass/assets/stylesheets/bootstrap/normalize";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/print";
//@import "~bootstrap-sass/assets/stylesheets/bootstrap/glyphicons";
// Core CSS
@import "~bootstrap-sass/assets/stylesheets/bootstrap/scaffolding";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/type";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/code";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/grid";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/tables";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/forms";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/buttons";
// Components
@import "~bootstrap-sass/assets/stylesheets/bootstrap/component-animations";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/dropdowns";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/button-groups";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/input-groups";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/navs";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/navbar";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/breadcrumbs";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/pagination";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/pager";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/labels";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/badges";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/jumbotron";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/thumbnails";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/alerts";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/progress-bars";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/media";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/list-group";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/panels";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/responsive-embed";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/wells";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/close";
// Components w/ JavaScript
@import "~bootstrap-sass/assets/stylesheets/bootstrap/modals";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/tooltip";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/popovers";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/carousel";
// Utility classes
@import "~bootstrap-sass/assets/stylesheets/bootstrap/utilities";
@import "~bootstrap-sass/assets/stylesheets/bootstrap/responsive-utilities";

Yay! Happy paths!

Next, in main.scss, import this file instead of the core one. Just, ./_bootstrap.scss.:

... lines 1 - 2
@import './_bootstrap.scss';
... lines 4 - 82

If this is all we did, nothing would change: we're still importing everything. But now... we have power! In _bootstrap.scss, comment out the glyphicons line:

... lines 1 - 7
//@import "~bootstrap-sass/assets/stylesheets/bootstrap/glyphicons";
... lines 9 - 51

Cool! We don't need to restart Webpack after this change, but, stop it temporarily so that we can clean out the build/ directory:

rm -rf web/build/*

Now, re-run webpack:

./node_modules/.bin/webpack --watch

Check it out! In web/build, we still have the Font Awesome fonts... but we do not have the glyphicon fonts anymore. That's awesome! We're not parsing the _glyphicons.scss file anymore, so Webpack never sees those font files and so never moves them. This is proof that our CSS file is now just a little bit smaller.

Ok, let's add some sourcemaps to make debugging a lot nicer.

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Default user avatar
Default user avatar Radoje Albijanic | posted 5 years ago

Hi folks,

I have phpStorm complaining about @import with `~` and marking error "Cannot resolve import into sass/scss file" when importing module assets. Any ideas?

1 Reply

Hey Radoje Albijanic!

Do you get an error from Webpack or just the warning from PhpStorm? Since the `~` thing is something special from Webpack, it's likely that PhpStorm just doesn't understand this syntax, which is unfortunate, but not a big problem :). You could also use the full path to a module - '../../node_modules/module_name/path/to/file.sass` - but it's kind of annoying ;).


Default user avatar
Default user avatar Radoje Albijanic | weaverryan | posted 5 years ago

Hey Ryan,

Webpack is cool, PhpStorm is the one making trouble :). Nothing special, its just annoying to see that red line, and i didnt see it in the video so I thought there is some catch :)

3 Reply

Ah yea. I'm a bit surprised that PhpStorm doesn't understand that syntax yet - they've improved their Webpack support, but it's not perfect yet, for sure!

Wei lun L. Avatar
Wei lun L. Avatar Wei lun L. | posted 5 years ago

When I change to $brand-primary: darken(#428bca, 2.5%); , It still #337ab7 . Why?
It didn't work anymore?


Hey Kevin,

Probably browser's cache? Try to open the page in Chrome Incognito mode, do you still see no changes?


Wei lun L. Avatar
Wei lun L. Avatar Wei lun L. | Victor | posted 5 years ago

Finally, I found my export path is wrong, thank you.


Hey Kevin,

Glad you got it working! And thank you for sharing your solution - it might be useful for other users.


Wei lun L. Avatar

"name": "javascript",
"version": "1.0.0",
"main": "index.js",
"repository": "git@github.com:knpuniversity/javascript.git",
"author": "Ryan Weaver <ryan@thatsquality.com>",
"license": "MIT",
"devDependencies": {
"@babel/core": "^7.1.2",
"@babel/preset-env": "^7.1.0",
"babel-loader": "^8.0.4",
"bootstrap-sass": "^3.3.7",
"copy-webpack-plugin": "^4.6.0",
"css-loader": "^1.0.0",
"file-loader": "^2.0.0",
"font-awesome": "^4.7.0",
"jquery": "^3.3.1",
"node-sass": "^4.10.0",
"resolve-url-loader": "^3.0.0",
"sass-loader": "^7.1.0",
"style-loader": "^0.23.1",
"sweetalert2": "^7.24.4",
"webpack": "^4.20.2",
"webpack-cli": "^3.1.2"
"dependencies": {
"babel-polyfill": "^6.26.0"

Wei lun L. Avatar

test: /\.scss$/,
use: [

Wei lun L. Avatar

$brand-primary: darken(#428bca, 2.5%) ; // #337ab7
$bootstrap-sass-asset-helper: true;

@import '~bootstrap-sass/assets/stylesheets/_bootstrap.scss';
@import '~font-awesome/css/font-awesome.css';

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This tutorial explains the concepts of an old version of Webpack using an old version of Symfony. The most important concepts are still the same, but you should expect significant differences in new versions.

What PHP libraries does this tutorial use?

// composer.json
    "require": {
        "php": "^7.2.0",
        "symfony/symfony": "3.3.*", // v3.3.16
        "twig/twig": "2.10.*", // v2.10.0
        "doctrine/orm": "^2.5", // v2.7.0
        "doctrine/doctrine-bundle": "^1.6", // 1.10.3
        "doctrine/doctrine-cache-bundle": "^1.2", // 1.3.5
        "symfony/swiftmailer-bundle": "^2.3", // v2.6.3
        "symfony/monolog-bundle": "^2.8", // v2.12.1
        "symfony/polyfill-apcu": "^1.0", // v1.4.0
        "sensio/distribution-bundle": "^5.0", // v5.0.22
        "sensio/framework-extra-bundle": "^3.0.2", // v3.0.26
        "incenteev/composer-parameter-handler": "^2.0", // v2.1.2
        "friendsofsymfony/user-bundle": "^2.0", // v2.1.2
        "doctrine/doctrine-fixtures-bundle": "~2.3", // v2.4.1
        "doctrine/doctrine-migrations-bundle": "^1.2", // v1.3.2
        "composer/package-versions-deprecated": "^1.11", // 1.11.99
        "friendsofsymfony/jsrouting-bundle": "^1.6" // 1.6.0
    "require-dev": {
        "sensio/generator-bundle": "^3.0", // v3.1.6
        "symfony/phpunit-bridge": "^3.0" // v3.3.5

What JavaScript libraries does this tutorial use?

// package.json
    "dependencies": [],
    "devDependencies": {
        "babel-core": "^6.25.0", // 6.25.0
        "babel-loader": "^7.1.1", // 7.1.1
        "babel-plugin-syntax-dynamic-import": "^6.18.0", // 6.18.0
        "babel-preset-env": "^1.6.0", // 1.6.0
        "bootstrap-sass": "^3.3.7", // 3.3.7
        "clean-webpack-plugin": "^0.1.16", // 0.1.16
        "copy-webpack-plugin": "^4.0.1", // 4.0.1
        "core-js": "^2.4.1", // 2.4.1
        "css-loader": "^0.28.4", // 0.28.4
        "extract-text-webpack-plugin": "^3.0.0", // 3.0.0
        "file-loader": "^0.11.2", // 0.11.2
        "font-awesome": "^4.7.0", // 4.7.0
        "jquery": "^3.2.1", // 3.2.1
        "lodash": "^4.17.4", // 4.17.4
        "node-sass": "^4.5.3", // 4.5.3
        "resolve-url-loader": "^2.1.0", // 2.1.0
        "sass-loader": "^6.0.6", // 6.0.6
        "style-loader": "^0.18.2", // 0.18.2
        "sweetalert2": "^6.6.6", // 6.6.6
        "webpack": "^3.4.1", // 3.4.1
        "webpack-chunk-hash": "^0.4.0", // 0.4.0
        "webpack-dev-server": "^2.6.1", // 2.6.1
        "webpack-manifest-plugin": "^1.2.1" // 1.2.1