How to Override Bootstrap CSS

In the dynamic landscape of web design, Bootstrap stands tall as a beacon for developers seeking structure and simplicity. It’s the shorthand many of us turn to, and for good reason.

Yet, as we stroll through countless websites, a common theme emerges—a distinct ‘Bootstrap look’. It’s a uniform that, while clean and professional, often begs for individuality.

But here’s the thing: Bootstrap was never designed to confine, but to empower. It lays down the foundation, yes, but it’s on us to build up, to reimagine, to redefine. How do we then break away from the mold, you ask? By mastering the fine art of overriding its CSS.

It’s a journey from the generic to the iconic, from stock to signature. Let’s delve deep into how we can tailor Bootstrap to our unique vision, ensuring our websites stand out in a crowd, all while leveraging the strength of this formidable framework.

How do I override Bootstrap CSS?

What is Bootstrap CSS?

Bootstrap, a brainchild of Twitter, is a free, open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS, JavaScript, and (optionally) jQuery-based design templates for typography, forms, buttons, navigation, and other interface components. In simple terms, Bootstrap provides a foundation—a starting point—from which developers can craft impressive websites without starting from scratch.

Components of Bootstrap CSS: More than Just Styling

Bootstrap’s power lies in its wide range of components. From the familiar navigation bars and carousels to modals and popovers, these components are pre-styled and ready to be implemented. Here are some key components:

  • Grid System: The foundation of responsive design, enabling content arrangement in grid-based layouts.
  • Typography: Predefined classes for headings, paragraphs, lists, and more.
  • Buttons: Various sizes, states, and colors, all customizable.
  • Forms: Styled inputs, checkboxes, selects, and more.
  • Navigation: Navbars, tabs, pills, and breadcrumb trails.
  • Media: Carousels, modals, and responsive embeds for multimedia content.

Techniques with Bootstrap CSS: Breaking the Mold

While Bootstrap provides a sturdy foundation, customization is where your website truly stands out. Here are techniques to override Bootstrap’s CSS:

  • Custom CSS File: The simplest method After linking Bootstrap’s CSS, link your custom CSS file. Any styles you define will override Bootstrap’s default styles.
  • SASS/LESS Variables: Bootstrap is built with preprocessors. By altering these variables, you can redefine aspects like color schemes and spacing.
  • Bootstrap’s Customizer is an official tool where you can tweak the components you need and customize their design before downloading.

Also, Read: 115 Best Free Responsive CSS Cards In 2023

Overriding Bootstrap CSS: Step-by-Step Guide

To truly make a Bootstrap-based website your own, you’ll often need to override its default styles. Here’s how you can do that efficiently:

Use a Custom CSS File


  • Setup: After integrating Bootstrap’s CSS link in your HTML, create a new CSS file. Name it something recognizable, like “custom.css”.
  • Link: Ensure you link your “custom.css” file after Bootstrap’s CSS link. This is crucial because CSS cascades; styles declared later override those declared earlier.
  • Override: Now, in your “custom.css” file, redefine any Bootstrap class you wish to customize.


<!-- Linking Bootstrap CSS -->
<link rel="stylesheet" href="path-to-bootstrap-css">

<!-- Linking Custom CSS -->
<link rel="stylesheet" href="path-to-custom-css">

Leverage Specificity

In CSS, specificity determines which styles are applied. By using more specific selectors, you can ensure your styles take precedence over Bootstrap’s.

Example: If Bootstrap defines:

.btn { background-color: blue; }

You can override it with:

body .btn { background-color: red; }

Utilize !important (Sparingly)

The “!important” declaration in CSS ensures a style is applied, overriding any other conflicting styles. However, it’s a heavy-handed approach and can make future changes tricky. Use it as a last resort.


.custom-btn {
    background-color: green !important;

Customize with SASS or Less

Bootstrap’s source files use SASS (previously LESS in older versions). By altering its variables and mixins, you can create a custom build of Bootstrap tailored to your needs.


  • Download Source: Get Bootstrap’s source files, which include the SASS files.
  • Tweak Variables: Modify the “_variables.scss” file to change default values.
  • Compile: Use a SASS compiler to generate a new CSS file with your custom styles.

Bootstrap’s Customizer

For those who prefer a GUI, Bootstrap offers a customizer where you can select components, tweak variables, and download a personalized version.


  • Visit: Go to Bootstrap’s official Customizer page.
  • Customize: Choose which components you want and modify the default variables.
  • Download: Get your personalized Bootstrap build.

The Advantages of Using Bootstrap CSS: Why It Reigns

Bootstrap isn’t just popular—it’s beneficial.

  • Speed: Rapid prototyping becomes a breeze.
  • Responsiveness: A mobile-first approach ensures designs look great on all devices.
  • Consistency: Originally built to address Twitter’s consistency issues, it ensures a uniform look across platforms.
  • Customizability: As we’ve discussed, overriding its styles is straightforward.
  • Community Support: A vast community means extensive documentation, updates, and third-party tools.

The Limitations of Bootstrap CSS: A Balanced View

Every tool has its drawbacks, and Bootstrap is no exception:

  • Sameness: Without customization, many Bootstrap websites can look eerily similar.
  • File Size: Though modular, if not optimized, Bootstrap can be bulky.
  • Learning Curve: While it’s easier than starting from scratch, there’s still a learning phase.
  • JavaScript Reliance: Some of Bootstrap’s components rely on JavaScript, which can be a concern for those prioritizing speed or avoiding JS.


Bootstrap offers an unparalleled blend of flexibility and ease, but its true potential shines when developers go the extra mile to customize and override its default styles. By understanding its strengths and limitations, we not only utilize the framework more effectively but also craft websites that are genuinely unique and outstanding in the vast digital ocean. Dive deep, explore, and let your creativity override the defaults.

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