CSS
Global CSS settings, fundamental HTML elements styled and enhanced with extensible classes, and an advanced grid system.
Global CSS settings, fundamental HTML elements styled and enhanced with extensible classes, and an advanced grid system.
Get the lowdown on the key pieces of Bootstrap's infrastructure, including our approach to better, faster, stronger web development.
Bootstrap makes use of certain HTML elements and CSS properties that require the use of the HTML5 doctype. Include it at the beginning of all your projects.
With Bootstrap 2, we added optional mobile friendly styles for key aspects of the framework. With Bootstrap 3, we've rewritten the project to be mobile friendly from the start. Instead of adding on optional mobile styles, they're baked right into the core. In fact, Bootstrap is mobile first. Mobile first styles can be found throughout the entire library instead of in separate files.
To ensure proper rendering and touch zooming,
add the viewport meta tag to your
<head>
.
You can disable zooming capabilities on mobile devices by adding
user-scalable=no
to the viewport meta tag. This
disables zooming, meaning users are only able to scroll, and
results in your site feeling a bit more like a native application.
Overall, we don't recommend this on every site, so use caution!
Bootstrap sets basic global display, typography, and link styles. Specifically, we:
background-color: #fff;
on the
body
@font-family-base
,
@font-size-base
, and
@line-height-base
attributes as our typographic
base
@link-color
and apply
link underlines only on :hover
These styles can be found within scaffolding.less
.
For improved cross-browser rendering, we use Normalize.css, a project by Nicolas Gallagher and Jonathan Neal.
Bootstrap requires a containing element to wrap site contents and
house our grid system. You may choose one of two containers to use
in your projects. Note that, due to padding
and more,
neither container is nestable.
Use .container
for a responsive fixed width
container.
Use .container-fluid
for a full width container,
spanning the entire width of your viewport.
Bootstrap includes a responsive, mobile first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful mixins for generating more semantic layouts.
Grid systems are used for creating page layouts through a series of rows and columns that house your content. Here's how the Bootstrap grid system works:
.container
(fixed-width) or
.container-fluid
(full-width) for proper alignment
and padding.
.row
and
.col-xs-4
are available for quickly making grid
layouts. Less mixins can also be used for more semantic layouts.
padding
. That padding is offset in rows for the
first and last column via negative margin on .row
s.
.col-xs-4
.
.col-md-*
class to an element will not only affect
its styling on medium devices but also on large devices if a
.col-lg-*
class is not present.
Look to the examples for applying these principles to your code.
We use the following media queries in our Less files to create the key breakpoints in our grid system.
We occasionally expand on these media queries to include a
max-width
to limit CSS to a narrower set of devices.
See how aspects of the Bootstrap grid system work across multiple devices with a handy table.
Extra small devices Phones (<768px) | Small devices Tablets (≥768px) | Medium devices Desktops (≥992px) | Large devices Desktops (≥1200px) | |
---|---|---|---|---|
Grid behavior | Horizontal at all times | Collapsed to start, horizontal above breakpoints | ||
Container width | None (auto) | 750px | 970px | 1170px |
Class prefix | .col-xs- |
.col-sm- |
.col-md- |
.col-lg- |
# of columns | 12 | |||
Column width | Auto | ~62px | ~81px | ~97px |
Gutter width | 30px (15px on each side of a column) | |||
Nestable | Yes | |||
Offsets | Yes | |||
Column ordering | Yes |
Using a single set of .col-md-*
grid classes, you can
create a basic grid system that starts out stacked on mobile
devices and tablet devices (the extra small to small range) before
becoming horizontal on desktop (medium) devices. Place grid
columns in any .row
.
Turn any fixed-width grid layout into a full-width layout by
changing your outermost .container
to
.container-fluid
.
Don't want your columns to simply stack in smaller devices? Use
the extra small and medium device grid classes by adding
.col-xs-*
.col-md-*
to your columns. See
the example below for a better idea of how it all works.
Build on the previous example by creating even more dynamic and
powerful layouts with tablet .col-sm-*
classes.
If more than 12 columns are placed within a single row, each group of extra columns will, as one unit, wrap onto a new line.
With the four tiers of grids available you're bound to run into
issues where, at certain breakpoints, your columns don't clear
quite right as one is taller than the other. To fix that, use a
combination of a .clearfix
and our
responsive utility classes.
In addition to column clearing at responsive breakpoints, you may need to reset offsets, pushes, or pulls. See this in action in the grid example.
Remove the gutters from a row and it's columns with the
.row-no-gutters
class.
Move columns to the right using
.col-md-offset-*
classes. These classes increase the
left margin of a column by *
columns. For example,
.col-md-offset-4
moves .col-md-4
over
four columns.
You can also override offsets from lower grid tiers with
.col-*-offset-0
classes.
To nest your content with the default grid, add a new
.row
and set of .col-sm-*
columns within
an existing .col-sm-*
column. Nested rows should
include a set of columns that add up to 12 or fewer (it is not
required that you use all 12 available columns).
Easily change the order of our built-in grid columns with
.col-md-push-*
and
.col-md-pull-*
modifier classes.
In addition to prebuilt grid classes for fast layouts, Bootstrap includes Less variables and mixins for quickly generating your own simple, semantic layouts.
Variables determine the number of columns, the gutter width, and the media query point at which to begin floating columns. We use these to generate the predefined grid classes documented above, as well as for the custom mixins listed below.
Mixins are used in conjunction with the grid variables to generate semantic CSS for individual grid columns.
You can modify the variables to your own custom values, or just use the mixins with their default values. Here's an example of using the default settings to create a two-column layout with a gap between.
All HTML headings, <h1>
through
<h6>
, are available. .h1
through
.h6
classes are also available, for when you want to
match the font styling of a heading but still want your text to be
displayed inline.
h1. Bootstrap heading |
Semibold 36px |
h2. Bootstrap heading |
Semibold 30px |
h3. Bootstrap heading |
Semibold 24px |
h4. Bootstrap heading |
Semibold 18px |
h5. Bootstrap heading |
Semibold 14px |
h6. Bootstrap heading |
Semibold 12px |
Create lighter, secondary text in any heading with a generic
<small>
tag or the .small
class.
h1. Bootstrap heading Secondary text |
h2. Bootstrap heading Secondary text |
h3. Bootstrap heading Secondary text |
h4. Bootstrap heading Secondary text |
h5. Bootstrap heading Secondary text |
h6. Bootstrap heading Secondary text |
Bootstrap's global default font-size
is
14px, with a line-height
of
1.428. This is applied to the
<body>
and all paragraphs. In addition,
<p>
(paragraphs) receive a bottom margin of
half their computed line-height (10px by default).
Nullam quis risus eget urna mollis ornare vel eu leo. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Nullam id dolor id nibh ultricies vehicula.
Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec ullamcorper nulla non metus auctor fringilla. Duis mollis, est non commodo luctus, nisi erat porttitor ligula, eget lacinia odio sem nec elit. Donec ullamcorper nulla non metus auctor fringilla.
Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Duis mollis, est non commodo luctus, nisi erat porttitor ligula, eget lacinia odio sem nec elit.
Make a paragraph stand out by adding .lead
.
Vivamus sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Duis mollis, est non commodo luctus.
The typographic scale is based on two Less variables in
variables.less: @font-size-base
and
@line-height-base
. The first is the base font-size
used throughout and the second is the base line-height. We use
those variables and some simple math to create the margins,
paddings, and line-heights of all our type and more. Customize
them and Bootstrap adapts.
For highlighting a run of text due to its relevance in another
context, use the <mark>
tag.
You can use the mark tag to highlight text.
For indicating blocks of text that have been deleted use the
<del>
tag.
This line of text is meant to be treated as deleted
text.
For indicating blocks of text that are no longer relevant use the
<s>
tag.
This line of text is meant to be treated as no longer
accurate.
For indicating additions to the document use the
<ins>
tag.
This line of text is meant to be treated as an addition to the document.
To underline text use the <u>
tag.
This line of text will render as underlined
Make use of HTML's default emphasis tags with lightweight styles.
For de-emphasizing inline or blocks of text, use the
<small>
tag to set text at 85% the size of the
parent. Heading elements receive their own
font-size
for nested
<small>
elements.
You may alternatively use an inline element with
.small
in place of any <small>
.
This line of text is meant to be treated as fine print.
For emphasizing a snippet of text with a heavier font-weight.
The following snippet of text is rendered as bold text.
For emphasizing a snippet of text with italics.
The following snippet of text is rendered as italicized text.
Feel free to use <b>
and
<i>
in HTML5. <b>
is meant
to highlight words or phrases without conveying additional
importance while <i>
is mostly for voice,
technical terms, etc.
Easily realign text to components with text alignment classes.
Left aligned text.
Center aligned text.
Right aligned text.
Justified text.
No wrap text.
Transform text in components with text capitalization classes.
Lowercased text.
Uppercased text.
Capitalized text.
Stylized implementation of HTML's
<abbr>
element for abbreviations and acronyms
to show the expanded version on hover. Abbreviations with a
title
attribute have a light dotted bottom border and
a help cursor on hover, providing additional context on hover and
to users of assistive technologies.
An abbreviation of the word attribute is attr.
Add .initialism
to an abbreviation for a slightly
smaller font-size.
HTML is the best thing since sliced bread.
Present contact information for the nearest ancestor or the entire
body of work. Preserve formatting by ending all lines with
<br>
.
For quoting blocks of content from another source within your document.
Wrap <blockquote>
around any
HTML as the quote.
For straight quotes, we recommend a <p>
.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.
Style and content changes for simple variations on a standard
<blockquote>
.
Add a <footer>
for identifying the source. Wrap
the name of the source work in <cite>
.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.
Add .blockquote-reverse
for a blockquote with
right-aligned content.
A list of items in which the order does not explicitly matter.
A list of items in which the order does explicitly matter.
Remove the default list-style
and left margin on list
items (immediate children only).
This only applies to immediate children list items, meaning you will need to add the class for any nested lists as
well.
Place all list items on a single line with
display: inline-block;
and some light padding.
A list of terms with their associated descriptions.
Make terms and descriptions in <dl>
line up
side-by-side. Starts off stacked like default
<dl>
s, but when the navbar expands, so do
these.
Horizontal description lists will truncate terms that are too
long to fit in the left column with text-overflow
.
In narrower viewports, they will change to the default stacked
layout.
Wrap inline snippets of code with <code>
.
<section>
should be wrapped as
inline.
Use the <kbd>
to indicate input that is
typically entered via keyboard.
Use <pre>
for multiple lines of code. Be sure
to escape any angle brackets in the code for proper rendering.
<p>Sample text here...</p>
You may optionally add the .pre-scrollable
class,
which will set a max-height of 350px and provide a y-axis
scrollbar.
For indicating variables use the <var>
tag.
y = mx + b
For indicating blocks sample output from a program use the
<samp>
tag.
This text is meant to be treated as sample output from a computer program.
For basic styling—light padding and only horizontal
dividers—add the base class .table
to any
<table>
. It may seem super redundant, but given
the widespread use of tables for other plugins like calendars and
date pickers, we've opted to isolate our custom table styles.
# | First Name | Last Name | Username |
---|---|---|---|
1 | Mark | Otto | @mdo |
2 | Jacob | Thornton | @fat |
3 | Larry | the Bird |
Use .table-striped
to add zebra-striping to any table
row within the <tbody>
.
Striped tables are styled via the :nth-child
CSS
selector, which is not available in Internet Explorer 8.
# | First Name | Last Name | Username |
---|---|---|---|
1 | Mark | Otto | @mdo |
2 | Jacob | Thornton | @fat |
3 | Larry | the Bird |
Add .table-bordered
for borders on all sides of the
table and cells.
# | First Name | Last Name | Username |
---|---|---|---|
1 | Mark | Otto | @mdo |
2 | Jacob | Thornton | @fat |
3 | Larry | the Bird |
Add .table-hover
to enable a hover state on table
rows within a <tbody>
.
# | First Name | Last Name | Username |
---|---|---|---|
1 | Mark | Otto | @mdo |
2 | Jacob | Thornton | @fat |
3 | Larry | the Bird |
Add .table-condensed
to make tables more compact by
cutting cell padding in half.
# | First Name | Last Name | Username |
---|---|---|---|
1 | Mark | Otto | @mdo |
2 | Jacob | Thornton | @fat |
3 | Larry the Bird |
Use contextual classes to color table rows or individual cells.
Class | Description |
---|---|
.active
|
Applies the hover color to a particular row or cell |
.success
|
Indicates a successful or positive action |
.info
|
Indicates a neutral informative change or action |
.warning
|
Indicates a warning that might need attention |
.danger
|
Indicates a dangerous or potentially negative action |
# | Column heading | Column heading | Column heading |
---|---|---|---|
1 | Column content | Column content | Column content |
2 | Column content | Column content | Column content |
3 | Column content | Column content | Column content |
4 | Column content | Column content | Column content |
5 | Column content | Column content | Column content |
6 | Column content | Column content | Column content |
7 | Column content | Column content | Column content |
8 | Column content | Column content | Column content |
9 | Column content | Column content | Column content |
Using color to add meaning to a table row or individual cell
only provides a visual indication, which will not be conveyed to
users of assistive technologies โ such as screen readers. Ensure
that information denoted by the color is either obvious from the
content itself (the visible text in the relevant table
row/cell), or is included through alternative means, such as
additional text hidden with the .sr-only
class.
Create responsive tables by wrapping any .table
in
.table-responsive
to make them scroll horizontally on
small devices (under 768px). When viewing on anything larger than
768px wide, you will not see any difference in these tables.
Responsive tables make use of overflow-y: hidden
,
which clips off any content that goes beyond the bottom or top
edges of the table. In particular, this can clip off dropdown
menus and other third-party widgets.
Firefox has some awkward fieldset styling involving
width
that interferes with the responsive table.
This cannot be overridden without a Firefox-specific hack that
we don't provide in Bootstrap:
For more information, read this Stack Overflow answer.
# | Table heading | Table heading | Table heading | Table heading | Table heading | Table heading |
---|---|---|---|---|---|---|
1 | Table cell | Table cell | Table cell | Table cell | Table cell | Table cell |
2 | Table cell | Table cell | Table cell | Table cell | Table cell | Table cell |
3 | Table cell | Table cell | Table cell | Table cell | Table cell | Table cell |
# | Table heading | Table heading | Table heading | Table heading | Table heading | Table heading |
---|---|---|---|---|---|---|
1 | Table cell | Table cell | Table cell | Table cell | Table cell | Table cell |
2 | Table cell | Table cell | Table cell | Table cell | Table cell | Table cell |
3 | Table cell | Table cell | Table cell | Table cell | Table cell | Table cell |
Individual form controls automatically receive some global
styling. All textual <input>
,
<textarea>
, and
<select>
elements with
.form-control
are set to width: 100%;
by
default. Wrap labels and controls in .form-group
for
optimum spacing.
Do not mix form groups directly with input groups. Instead, nest the input group inside of the form group.
Add .form-inline
to your form (which doesn't have to
be a <form>
) for left-aligned and inline-block
controls.
This only applies to forms within viewports that are at least
768px wide.
Inputs and selects have width: 100%;
applied by
default in Bootstrap. Within inline forms, we reset that to
width: auto;
so multiple controls can reside on the
same line. Depending on your layout, additional custom widths
may be required.
Screen readers will have trouble with your forms if you don't
include a label for every input. For these inline forms, you can
hide the labels using the .sr-only
class. There are
further alternative methods of providing a label for assistive
technologies, such as the aria-label
,
aria-labelledby
or title
attribute. If
none of these is present, screen readers may resort to using the
placeholder
attribute, if present, but note that
use of placeholder
as a replacement for other
labelling methods is not advised.
Use Bootstrap's predefined grid classes to align labels and groups
of form controls in a horizontal layout by adding
.form-horizontal
to the form (which doesn't have to
be a <form>
). Doing so changes
.form-group
s to behave as grid rows, so no need for
.row
.
Examples of standard form controls supported in an example form layout.
Most common form control, text-based input fields. Includes
support for all HTML5 types: text
,
password
, datetime
,
datetime-local
, date
,
month
, time
, week
,
number
, email
, url
,
search
, tel
, and color
.
Inputs will only be fully styled if their type
is
properly declared.
To add integrated text or buttons before and/or after any
text-based <input>
,
check out the input group component.
Form control which supports multiple lines of text. Change
rows
attribute as necessary.
Checkboxes are for selecting one or several options in a list, while radios are for selecting one option from many.
Disabled checkboxes and radios are supported, but to provide a
"not-allowed" cursor on hover of the parent
<label>
, you'll need to add the
.disabled
class to the parent .radio
,
.radio-inline
, .checkbox
, or
.checkbox-inline
.
Use the .checkbox-inline
or
.radio-inline
classes on a series of checkboxes or
radios for controls that appear on the same line.
Should you have no text within the <label>
, the
input is positioned as you'd expect.
Currently only works on non-inline checkboxes and
radios.
Remember to still provide some form of label for assistive
technologies (for instance, using aria-label
).
Note that many native select menusโnamely in Safari and
Chromeโhave rounded corners that cannot be modified via
border-radius
properties.
For <select>
controls with the
multiple
attribute, multiple options are shown by
default.
When you need to place plain text next to a form label within a
form, use the .form-control-static
class on a
<p>
.
We remove the default outline
styles on some form
controls and apply a box-shadow
in its place for
:focus
.
:focus
state
The above example input uses custom styles in our documentation
to demonstrate the :focus
state on a
.form-control
.
Add the disabled
boolean attribute on an input to
prevent user interactions. Disabled inputs appear lighter and add
a not-allowed
cursor.
Add the disabled
attribute to a
<fieldset>
to disable all the controls within
the <fieldset>
at once.
<a>
By default, browsers will treat all native form controls
(<input>
, <select>
and
<button>
elements) inside a
<fieldset disabled>
as disabled, preventing
both keyboard and mouse interactions on them. However, if your
form also includes
<a ... class="btn btn-*">
elements, these
will only be given a style of pointer-events: none
.
As noted in the section about
disabled state for buttons (and
specifically in the sub-section for anchor elements), this CSS
property is not yet standardized and isn't fully supported in
Opera 18 and below, or in Internet Explorer 11, and won't
prevent keyboard users from being able to focus or activate
these links. So to be safe, use custom JavaScript to disable
such links.
While Bootstrap will apply these styles in all browsers,
Internet Explorer 11 and below don't fully support the
disabled
attribute on a
<fieldset>
. Use custom JavaScript to disable
the fieldset in these browsers.
Add the readonly
boolean attribute on an input to
prevent modification of the input's value. Read-only inputs appear
lighter (just like disabled inputs), but retain the standard
cursor.
Block level help text for form controls.
Help text should be explicitly associated with the form control
it relates to using the aria-describedby
attribute.
This will ensure that assistive technologies โ such as screen
readers โ will announce this help text when the user focuses or
enters the control.
Bootstrap includes validation styles for error, warning, and success
states on form controls. To use, add .has-warning
,
.has-error
, or .has-success
to the parent
element. Any .control-label
,
.form-control
, and .help-block
within that
element will receive the validation styles.
Using these validation styles to denote the state of a form control only provides a visual, color-based indication, which will not be conveyed to users of assistive technologies - such as screen readers - or to colorblind users.
Ensure that an alternative indication of state is also provided.
For instance, you can include a hint about state in the form
control's <label>
text itself (as is the case
in the following code example), include a
Glyphicon (with
appropriate alternative text using the .sr-only
class
- see the
Glyphicon examples), or by providing an additional
help text block. Specifically for
assistive technologies, invalid form controls can also be assigned
an aria-invalid="true"
attribute.
You can also add optional feedback icons with the addition of
.has-feedback
and the right icon.
Feedback icons only work with textual
<input class="form-control">
elements.
Manual positioning of feedback icons is required for inputs
without a label and for
input groups with
an add-on on the right. You are strongly encouraged to provide
labels for all inputs for accessibility reasons. If you wish to
prevent labels from being displayed, hide them with the
.sr-only
class. If you must do without labels, adjust
the top
value of the feedback icon. For input groups,
adjust the right
value to an appropriate pixel value
depending on the width of your addon.
To ensure that assistive technologies โ such as screen readers โ
correctly convey the meaning of an icon, additional hidden text
should be included with the .sr-only
class and
explicitly associated with the form control it relates to using
aria-describedby
. Alternatively, ensure that the
meaning (for instance, the fact that there is a warning for a
particular text entry field) is conveyed in some other form, such
as changing the text of the actual
<label>
associated with the form control.
Although the following examples already mention the validation
state of their respective form controls in the
<label>
text itself, the above technique (using
.sr-only
text and aria-describedby
) has
been included for illustrative purposes.
.sr-only
labels
If you use the .sr-only
class to hide a form control's
<label>
(rather than using other labelling
options, such as the aria-label
attribute), Bootstrap
will automatically adjust the position of the icon once it's been
added.
Set heights using classes like .input-lg
, and set
widths using grid column classes like .col-lg-*
.
Create taller or shorter form controls that match button sizes.
Quickly size labels and form controls within
.form-horizontal
by adding
.form-group-lg
or .form-group-sm
.
Wrap inputs in grid columns, or any custom parent element, to easily enforce desired widths.
Use the button classes on an <a>
,
<button>
, or
<input>
element.
While button classes can be used on <a>
and
<button>
elements, only
<button>
elements are supported within our
nav and navbar components.
If the <a>
elements are used to act as
buttons โ triggering in-page functionality, rather than
navigating to another document or section within the current
page โ they should also be given an appropriate
role="button"
.
As a best practice,
we highly recommend using the
<button>
element whenever possible
to ensure matching cross-browser rendering.
Among other things, there's
a bug in Firefox <30
that prevents us from setting the line-height
of
<input>
-based buttons, causing them to not
exactly match the height of other buttons on Firefox.
Use any of the available button classes to quickly create a styled button.
Using color to add meaning to a button only provides a visual
indication, which will not be conveyed to users of assistive
technologies โ such as screen readers. Ensure that information
denoted by the color is either obvious from the content itself
(the visible text of the button), or is included through
alternative means, such as additional text hidden with the
.sr-only
class.
Fancy larger or smaller buttons? Add .btn-lg
,
.btn-sm
, or .btn-xs
for additional
sizes.
Create block level buttons—those that span the full width of
a parent— by adding .btn-block
.
Buttons will appear pressed (with a darker background, darker
border, and inset shadow) when active. For
<button>
elements, this is done via
:active
. For <a>
elements, it's
done with .active
. However, you may use
.active
on <button>
s (and include
the aria-pressed="true"
attribute) should you need to
replicate the active state programmatically.
No need to add :active
as it's a pseudo-class, but if
you need to force the same appearance, go ahead and add
.active
.
Add the .active
class to
<a>
buttons.
Make buttons look unclickable by fading them back with
opacity
.
Add the disabled
attribute to
<button>
buttons.
If you add the disabled
attribute to a
<button>
, Internet Explorer 9 and below will
render text gray with a nasty text-shadow that we cannot fix.
Add the .disabled
class to
<a>
buttons.
We use .disabled
as a utility class here, similar to
the common .active
class, so no prefix is required.
This class uses pointer-events: none
to try to
disable the link functionality of <a>
s, but
that CSS property is not yet standardized and isn't fully
supported in Opera 18 and below, or in Internet Explorer 11. In
addition, even in browsers that do support
pointer-events: none
, keyboard navigation remains
unaffected, meaning that sighted keyboard users and users of
assistive technologies will still be able to activate these
links. So to be safe, use custom JavaScript to disable such
links.
Images in Bootstrap 3 can be made responsive-friendly via the
addition of the .img-responsive
class. This applies
max-width: 100%;
, height: auto;
and
display: block;
to the image so that it scales nicely
to the parent element.
To center images which use the .img-responsive
class,
use .center-block
instead of
.text-center
.
See the helper classes section
for more details about .center-block
usage.
In Internet Explorer 8-10, SVG images with
.img-responsive
are disproportionately sized. To
fix this, add width: 100% \9;
where necessary.
Bootstrap doesn't apply this automatically as it causes
complications to other image formats.
Add classes to an <img>
element to easily style
images in any project.
Keep in mind that Internet Explorer 8 lacks support for rounded corners.
Convey meaning through color with a handful of emphasis utility classes. These may also be applied to links and will darken on hover just like our default link styles.
Fusce dapibus, tellus ac cursus commodo, tortor mauris nibh.
Nullam id dolor id nibh ultricies vehicula ut id elit.
Duis mollis, est non commodo luctus, nisi erat porttitor ligula.
Maecenas sed diam eget risus varius blandit sit amet non magna.
Etiam porta sem malesuada magna mollis euismod.
Donec ullamcorper nulla non metus auctor fringilla.
Sometimes emphasis classes cannot be applied due to the
specificity of another selector. In most cases, a sufficient
workaround is to wrap your text in a
<span>
with the class.
Using color to add meaning only provides a visual indication,
which will not be conveyed to users of assistive technologies โ
such as screen readers. Ensure that information denoted by the
color is either obvious from the content itself (the contextual
colors are only used to reinforce meaning that is already
present in the text/markup), or is included through alternative
means, such as additional text hidden with the
.sr-only
class.
Similar to the contextual text color classes, easily set the background of an element to any contextual class. Anchor components will darken on hover, just like the text classes.
Nullam id dolor id nibh ultricies vehicula ut id elit.
Duis mollis, est non commodo luctus, nisi erat porttitor ligula.
Maecenas sed diam eget risus varius blandit sit amet non magna.
Etiam porta sem malesuada magna mollis euismod.
Donec ullamcorper nulla non metus auctor fringilla.
Sometimes contextual background classes cannot be applied due to
the specificity of another selector. In some cases, a sufficient
workaround is to wrap your element's content in a
<div>
with the class.
As with contextual colors, ensure that any meaning conveyed through color is also conveyed in a format that is not purely presentational.
Use the generic close icon for dismissing content like modals and alerts.
Use carets to indicate dropdown functionality and direction. Note that the default caret will reverse automatically in dropup menus.
Float an element to the left or right with a class.
!important
is included to avoid specificity issues.
Classes can also be used as mixins.
Set an element to display: block
and center via
margin
. Available as a mixin and class.
Easily clear float
s by adding .clearfix
to the parent element. Utilizes
the micro clearfix
as popularized by Nicolas Gallagher. Can also be used as a mixin.
Force an element to be shown or hidden (including for screen readers) with the use of .show
and
.hidden
classes. These classes use
!important
to avoid specificity conflicts, just like
the quick floats. They are
only available for block level toggling. They can also be used as
mixins.
.hide
is available, but it does not always affect
screen readers and is deprecated as of v3.0.1.
Use .hidden
or .sr-only
instead.
Furthermore, .invisible
can be used to toggle only
the visibility of an element, meaning its display
is
not modified and the element can still affect the flow of the
document.
Hide an element to all devices
except screen readers with .sr-only
.
Combine .sr-only
with
.sr-only-focusable
to show the element again when
it's focused (e.g. by a keyboard-only user). Necessary for
following
accessibility best practices. Can also be used as mixins.
Utilize the .text-hide
class or mixin to help replace
an element's text content with a background image.
For faster mobile-friendly development, use these utility classes for showing and hiding content by device via media query. Also included are utility classes for toggling content when printed.
Try to use these on a limited basis and avoid creating entirely different versions of the same site. Instead, use them to complement each device's presentation.
Use a single or combination of the available classes for toggling content across viewport breakpoints.
Extra small devices Phones (<768px) | Small devices Tablets (≥768px) | Medium devices Desktops (≥992px) | Large devices Desktops (≥1200px) | |
---|---|---|---|---|
.visible-xs-* |
Visible | Hidden | Hidden | Hidden |
.visible-sm-* |
Hidden | Visible | Hidden | Hidden |
.visible-md-* |
Hidden | Hidden | Visible | Hidden |
.visible-lg-* |
Hidden | Hidden | Hidden | Visible |
.hidden-xs |
Hidden | Visible | Visible | Visible |
.hidden-sm |
Visible | Hidden | Visible | Visible |
.hidden-md |
Visible | Visible | Hidden | Visible |
.hidden-lg |
Visible | Visible | Visible | Hidden |
As of v3.2.0, the .visible-*-*
classes for each
breakpoint come in three variations, one for each CSS
display
property value listed below.
Group of classes | CSS display |
---|---|
.visible-*-block |
display: block; |
.visible-*-inline |
display: inline; |
.visible-*-inline-block |
display: inline-block; |
So, for extra small (xs
) screens for example, the
available .visible-*-*
classes are:
.visible-xs-block
, .visible-xs-inline
,
and .visible-xs-inline-block
.
The classes .visible-xs
, .visible-sm
,
.visible-md
, and .visible-lg
also exist,
but are deprecated as of v3.2.0. They are
approximately equivalent to .visible-*-block
, except
with additional special cases for toggling
<table>
-related elements.
Similar to the regular responsive classes, use these for toggling content for print.
Classes | Browser | |
---|---|---|
.visible-print-block .visible-print-inline .visible-print-inline-block
|
Hidden | Visible |
.hidden-print |
Visible | Hidden |
The class .visible-print
also exists but is
deprecated as of v3.2.0. It is approximately
equivalent to .visible-print-block
, except with
additional special cases for <table>
-related
elements.
Resize your browser or load on different devices to test the responsive utility classes.
Green checkmarks indicate the element is visible in your current viewport.
Here, green checkmarks also indicate the element is hidden in your current viewport.
Bootstrap's CSS is built on Less, a preprocessor with additional functionality like variables, mixins, and functions for compiling CSS. Those looking to use the source Less files instead of our compiled CSS files can make use of the numerous variables and mixins we use throughout the framework.
Grid variables and mixins are covered within the Grid system section.
Bootstrap can be used in at least two ways: with the compiled CSS or with the source Less files. To compile the Less files, consult the Getting Started section for how to setup your development environment to run the necessary commands.
Third party compilation tools may work with Bootstrap, but they are not supported by our core team.
Variables are used throughout the entire project as a way to centralize and share commonly used values like colors, spacing, or font stacks. For a complete breakdown, please see the Customizer.
Easily make use of two color schemes: grayscale and semantic. Grayscale colors provide quick access to commonly used shades of black while semantic include various colors assigned to meaningful contextual values.
Use any of these color variables as they are or reassign them to more meaningful variables for your project.
A handful of variables for quickly customizing key elements of your site's skeleton.
Easily style your links with the right color with only one value.
Note that the @link-hover-color
uses a function,
another awesome tool from Less, to automagically create the right
hover color. You can use darken
,
lighten
, saturate
, and
desaturate
.
Easily set your typeface, text size, leading, and more with a few quick variables. Bootstrap makes use of these as well to provide easy typographic mixins.
Two quick variables for customizing the location and filename of your icons.
Components throughout Bootstrap make use of some default variables for setting common values. Here are the most commonly used.
Vendor mixins are mixins to help support multiple browsers by including all relevant vendor prefixes in your compiled CSS.
Reset your components' box model with a single mixin. For context, see this helpful article from Mozilla.
The mixin is deprecated as of v3.2.0, with the introduction of Autoprefixer. To preserve backwards-compatibility, Bootstrap will continue to use the mixin internally until Bootstrap v4.
Today all modern browsers support the non-prefixed
border-radius
property. As such, there is no
.border-radius()
mixin, but Bootstrap does include
shortcuts for quickly rounding two corners on a particular side of
an object.
If your target audience is using the latest and greatest browsers
and devices, be sure to just use the
box-shadow
property on its own. If you need support
for older Android (pre-v4) and iOS devices (pre-iOS 5), use the
deprecated mixin to pick up the required
-webkit
prefix.
The mixin is deprecated as of v3.1.0, since Bootstrap doesn't officially support the outdated platforms that don't support the standard property. To preserve backwards-compatibility, Bootstrap will continue to use the mixin internally until Bootstrap v4.
Be sure to use rgba()
colors in your box shadows so
they blend as seamlessly as possible with backgrounds.
Multiple mixins for flexibility. Set all transition information with one, or specify a separate delay and duration as needed.
The mixins are deprecated as of v3.2.0, with the introduction of Autoprefixer. To preserve backwards-compatibility, Bootstrap will continue to use the mixins internally until Bootstrap v4.
Rotate, scale, translate (move), or skew any object.
The mixins are deprecated as of v3.2.0, with the introduction of Autoprefixer. To preserve backwards-compatibility, Bootstrap will continue to use the mixins internally until Bootstrap v4.
A single mixin for using all of CSS3's animation properties in one declaration and other mixins for individual properties.
The mixins are deprecated as of v3.2.0, with the introduction of Autoprefixer. To preserve backwards-compatibility, Bootstrap will continue to use the mixins internally until Bootstrap v4.
Set the opacity for all browsers and provide a
filter
fallback for IE8.
Provide context for form controls within each field.
Generate columns via CSS within a single element.
Easily turn any two colors into a background gradient. Get more advanced and set a direction, use three colors, or use a radial gradient. With a single mixin you get all the prefixed syntaxes you'll need.
You can also specify the angle of a standard two-color, linear gradient:
If you need a barber-stripe style gradient, that's easy, too. Just specify a single color and we'll overlay a translucent white stripe.
Up the ante and use three colors instead. Set the first color, the second color, the second color's color stop (a percentage value like 25%), and the third color with these mixins:
Heads up! Should you ever need to remove a
gradient, be sure to remove any IE-specific
filter
you may have added. You can do that by using
the .reset-filter()
mixin alongside
background-image: none;
.
Utility mixins are mixins that combine otherwise unrelated CSS properties to achieve a specific goal or task.
Forget adding class="clearfix"
to any element and
instead add the .clearfix()
mixin where appropriate.
Uses the
micro clearfix
from
Nicolas Gallagher.
Quickly center any element within its parent.
Requires width
or max-width
to be
set.
Specify the dimensions of an object more easily.
Easily configure the resize options for any textarea, or any other
element. Defaults to normal browser behavior (both
).
Easily truncate text with an ellipsis with a single mixin.
Requires element to be block
or
inline-block
level.
Specify two image paths and the @1x image dimensions, and Bootstrap will provide an @2x media query. If you have many images to serve, consider writing your retina image CSS manually in a single media query.
While Bootstrap is built on Less, it also has an official Sass port. We maintain it in a separate GitHub repository and handle updates with a conversion script.
Since the Sass port has a separate repo and serves a slightly different audience, the contents of the project differ greatly from the main Bootstrap project. This ensures the Sass port is as compatible with as many Sass-based systems as possible.
Path | Description |
---|---|
lib/ |
Ruby gem code (Sass configuration, Rails and Compass integrations) |
tasks/ |
Converter scripts (turning upstream Less to Sass) |
test/ |
Compilation tests |
templates/ |
Compass package manifest |
vendor/assets/ |
Sass, JavaScript, and font files |
Rakefile |
Internal tasks, such as rake and convert |
Visit the Sass port's GitHub repository to see these files in action.
For information on how to install and use Bootstrap for Sass, consult the GitHub repository readme. It's the most up to date source and includes information for use with Rails, Compass, and standard Sass projects.