You can apply button classes for hyperlinks (<a>)button elements (<button>), and inputs (<input>). You need to add class .btn to make a link or element look like a button. Bootstrap provides many options to style buttons.

For example,

<button type="button" class="btn btn-primary">Primary</button>

When using button classes on <a> elements that are used to trigger in-page functionality (like collapsing content), rather than linking to new pages or sections within the current page, these links should be given a role="button" to appropriately convey their purpose to assisstive technologies such as screen readers. For example,

<a class="btn btn-primary" href="#" role="button">Link</a>

Contextual Colors and Styles

  1. .btn-default
  2. .btn-primary
  3. .btn-success
  4. .btn-info
  5. .btn-warning
  6. .btn-danger
  7. .btn-light
  8. .btn-dark
  9. .btn-link

1. Outline Buttons

You can remove the background colors on button by replacing the class with the .btn-outline-*. For example,

<button type="button" class="btn btn-outline-warning">Warning</button>

2. Button Sizes

You can add .btn-lg or .btn-sm for additional sizes. For example,

<button type="button" class="btn btn-secondary btn-lg">Large button</button>

Bootstrap provides five button sizes:

  1. .btn-lg
  2. .btn-md
  3. .btn-sm
  4. .btn-xs
  5. .btn-block

You can also make a button span the full width of the parent element with the .btn-block class, changing the display of the button to block. For example,

<button type="button" class="btn btn-primary btn-lg btn-block">Block level button</button>

3. Button State: Active or Disabled

Buttons appear pressed (with a darker background, darker border, and inset shadow) when active. You can force the same active appearance with .active class. Also, include the aria-pressed="true" attribute. For example,

<a href="#" class="btn btn-primary btn-lg active" role="button" aria-pressed="true">Primary link</a>

You can make buttons look inactive by adding the disabled boolean attribute to any <button> element.

<button type="button" class="btn btn-secondary btn-lg" disabled>Button</button>

Disabled buttons using the <a> element behave a bit different:

For <a> elements, as they don’t support the disabled attribute, you have to add the .disabled class to make it visually appear disabled. Also, include the aria-disabled="true" attribute to indicate the state of the element. For example,

<a href="#" class="btn btn-primary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Primary link</a>

Sometimes, keyboard navigation remains unaffected, meaning that sighted keyboard users and users of assistive technologies can still be able to activate these links. So, to be safe, add a tabindex="-1" attribute on these links to prevent them from receiving keyboard focus and use custom JavaScript to disable their functionality.

4. Button Groups

Button group is a series of buttons together on a single line. You can wrap a series of buttons with .btn-group class. For example,

<div class="btn-group" role="group" aria-label="Basic example">
<button type="button" class="btn btn-secondary">Left</button>
<button type="button" class="btn btn-secondary">Middle</button>
<button type="button" class="btn btn-secondary">Right</button>

In order for assistive technologies (such as screen readers) to convey that a series of buttons is grouped, an appropriate role attribute needs to be provided. For button groups, this would be role="group", while toolbars should have a role="toolbar". In addition, groups and toolbars should be given an explicit label.

Sizing: Instead of applying button sizing classes to every button in a group, just add .btn-group-* to each .btn-group, including each one when nesting multiple groups. For example,

<div class="btn-group btn-group-lg" role="group" aria-label="...">...</div>

Vertical: You can make a set of buttons appear vertically stacked rather than horizontally by using class .btn-group-vertical. For example,

<div class="btn-group-vertical">

5. Button Toolbar

You can combine sets of button groups into button toolbars with the class .btn-toolbar. For example,

<div class="btn-toolbar" role="toolbar" aria-label="Toolbar with button groups">
<div class="btn-group mr-2" role="group" aria-label="First group">
<button type="button" class="btn btn-secondary">1</button>
<button type="button" class="btn btn-secondary">2</button>
<button type="button" class="btn btn-secondary">3</button>
<button type="button" class="btn btn-secondary">4</button>
<div class="btn-group mr-2" role="group" aria-label="Second group">
<button type="button" class="btn btn-secondary">5</button>
<button type="button" class="btn btn-secondary">6</button>
<button type="button" class="btn btn-secondary">7</button>
<div class="btn-group" role="group" aria-label="Third group">
<button type="button" class="btn btn-secondary">8</button>