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.
{% highlight html %} ... {% endhighlight %}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 :hoverThese 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 .rows..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.
{% highlight scss %} /* Extra small devices (phones, less than 768px) */ /* No media query since this is the default in Bootstrap */ /* Small devices (tablets, 768px and up) */ @media (min-width: @screen-sm-min) { ... } /* Medium devices (desktops, 992px and up) */ @media (min-width: @screen-md-min) { ... } /* Large devices (large desktops, 1200px and up) */ @media (min-width: @screen-lg-min) { ... } {% endhighlight %}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.
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.
{% highlight html %}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.
To nest your content with the default grid, add a new .row and set of .col-md-* columns within an existing .col-md-* column. Nested rows should include a set of columns that add up to 12 or less.
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.
{% highlight scss %} @grid-columns: 12; @grid-gutter-width: 30px; @grid-float-breakpoint: 768px; {% endhighlight %}Mixins are used in conjunction with the grid variables to generate semantic CSS for individual grid columns.
{% highlight scss %} // Creates a wrapper for a series of columns .make-row(@gutter: @grid-gutter-width) { // Then clear the floated columns .clearfix(); @media (min-width: @screen-sm-min) { margin-left: (@gutter / -2); margin-right: (@gutter / -2); } // Negative margin nested rows out to align the content of columns .row { margin-left: (@gutter / -2); margin-right: (@gutter / -2); } } // Generate the extra small columns .make-xs-column(@columns; @gutter: @grid-gutter-width) { position: relative; // Prevent columns from collapsing when empty min-height: 1px; // Inner gutter via padding padding-left: (@gutter / 2); padding-right: (@gutter / 2); // Calculate width based on number of columns available @media (min-width: @grid-float-breakpoint) { float: left; width: percentage((@columns / @grid-columns)); } } // Generate the small columns .make-sm-column(@columns; @gutter: @grid-gutter-width) { position: relative; // Prevent columns from collapsing when empty min-height: 1px; // Inner gutter via padding padding-left: (@gutter / 2); padding-right: (@gutter / 2); // Calculate width based on number of columns available @media (min-width: @screen-sm-min) { float: left; width: percentage((@columns / @grid-columns)); } } // Generate the small column offsets .make-sm-column-offset(@columns) { @media (min-width: @screen-sm-min) { margin-left: percentage((@columns / @grid-columns)); } } .make-sm-column-push(@columns) { @media (min-width: @screen-sm-min) { left: percentage((@columns / @grid-columns)); } } .make-sm-column-pull(@columns) { @media (min-width: @screen-sm-min) { right: percentage((@columns / @grid-columns)); } } // Generate the medium columns .make-md-column(@columns; @gutter: @grid-gutter-width) { position: relative; // Prevent columns from collapsing when empty min-height: 1px; // Inner gutter via padding padding-left: (@gutter / 2); padding-right: (@gutter / 2); // Calculate width based on number of columns available @media (min-width: @screen-md-min) { float: left; width: percentage((@columns / @grid-columns)); } } // Generate the medium column offsets .make-md-column-offset(@columns) { @media (min-width: @screen-md-min) { margin-left: percentage((@columns / @grid-columns)); } } .make-md-column-push(@columns) { @media (min-width: @screen-md-min) { left: percentage((@columns / @grid-columns)); } } .make-md-column-pull(@columns) { @media (min-width: @screen-md-min) { right: percentage((@columns / @grid-columns)); } } // Generate the large columns .make-lg-column(@columns; @gutter: @grid-gutter-width) { position: relative; // Prevent columns from collapsing when empty min-height: 1px; // Inner gutter via padding padding-left: (@gutter / 2); padding-right: (@gutter / 2); // Calculate width based on number of columns available @media (min-width: @screen-lg-min) { float: left; width: percentage((@columns / @grid-columns)); } } // Generate the large column offsets .make-lg-column-offset(@columns) { @media (min-width: @screen-lg-min) { margin-left: percentage((@columns / @grid-columns)); } } .make-lg-column-push(@columns) { @media (min-width: @screen-lg-min) { left: percentage((@columns / @grid-columns)); } } .make-lg-column-pull(@columns) { @media (min-width: @screen-lg-min) { right: percentage((@columns / @grid-columns)); } } {% endhighlight %}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.
{% highlight scss %} .wrapper { .make-row(); } .content-main { .make-lg-column(8); } .content-secondary { .make-lg-column(3); .make-lg-column-offset(1); } {% endhighlight %} {% highlight html %}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.
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{% endhighlight %}Make a paragraph stand out by adding .lead.
Vivamus sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Duis mollis, est non commodo luctus.
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{% endhighlight %}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 indicating blocks of text that have been deleted 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 is 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.
Left aligned text.
Center aligned text.
Right aligned text.
Justified text.
{% endhighlight %}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.
For expanded text on long hover of an abbreviation, include the title attribute with the <abbr> element.
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.
{% endhighlight %}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.
{% endhighlight %}Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.
Add .blockquote-reverse for a blockquote with right-aligned content.
...{% endhighlight %}
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.
<section> should be wrapped as inline.
{% endhighlight %}
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>
<p>Sample text here...</p>{% endhighlight %}
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 |
| Mark | Otto | @TwBootstrap | |
| 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 |
Create responsive tables by wrapping any .table in .table-responsive to make them scroll horizontally up to small devices (under 768px). When viewing on anything larger than 768px wide, you will not see any difference in these tables.
| # | 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> for left-aligned and inline-block controls. This only applies to forms within viewports that are at least 768px wide.
Inputs, selects, and textareas are 100% wide by default in Bootstrap. To use the inline form, you'll have to set a width on the form controls used within.
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.
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. Doing so changes .form-groups 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.
Use the .checkbox-inline or .radio-inline classes on a series of checkboxes or radios for controls that appear on the same line.
Use the default option, or add multiple to show multiple options at once.
When you need to place plain text next to a form label within a horizontal 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 stateThe 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 input and trigger a slightly different look.
Add the disabled attribute to a <fieldset> to disable all the controls within the <fieldset> at once.
<a>Our styles use pointer-events: none to try to disable the link functionality of <a class="btn btn-*"> buttons in this case, but that CSS property is not yet standardized and isn't fully supported in Opera 18 and below, or in Internet Explorer 11. So to be safe, use custom JavaScript to disable such links.
While Bootstrap will apply these styles in all browsers, Internet Explorer 9 and below don't actually 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 user input and style the input as disabled.
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.
You can also add optional feedback icons with the addition of .has-feedback and the right icon.
Manual positioning of feedback icons is required for input groups with an add-on on the right and inputs without a label. For input groups, adjust the right value to an appropriate pixel value depending on the width of your addon. For labels, adjust the topvalue.
Optional icons also work on horizontal and inline forms.
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.
Wrap inputs in grid columns, or any custom parent element, to easily enforce desired widths.
Block level help text for form controls.
Use any of the available button classes to quickly create a styled button.
Fancy larger or smaller buttons? Add .btn-lg, .btn-sm, or .btn-xs for additional sizes.
{% endhighlight %}
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 should you need to replicate the active state progammatically.
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.
{% highlight html %} {% endhighlight %}
Add the .active class to <a> buttons.
Make buttons look unclickable by fading them back 50%.
Add the disabled attribute to <button> buttons.
{% highlight html %} {% endhighlight %}
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. So to be safe, use custom JavaScript to disable such links.
While button classes can be used on <a> and <button> elements, only <button> elements are supported within our nav and navbar components.
Use the button classes on an <a>, <button>, or <input> element.
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 Firefox bug 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.
Images in Bootstrap 3 can be made responsive-friendly via the addition of the .img-responsive class. This applies max-width: 100%; and height: auto; to the image so that it scales nicely to the parent element.
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.
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{% endhighlight %}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.
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.
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{% endhighlight %}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.
To align components in navbars with utility classes, use .navbar-left or .navbar-right instead. See the navbar docs for details.
Set an element to display: block and center via margin. Available as a mixin and class.
Clear the float on any element with the .clearfix class. 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, the .visible-*-* classes for each breakpoint come in three variations, one for each CSS display property value listed below for visibility classes.
| 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. 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 v3.1.0. 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, visit the README 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.
{% highlight scss %} // Use as-is .masthead { background-color: @brand-primary; } // Reassigned variables in Less @alert-message-background: @brand-info; .alert { background-color: @alert-message-background; } {% endhighlight %}A handful of variables for quickly customizing key elements of your site's skeleton.
{% highlight scss %} // Scaffolding @body-bg: #fff; @text-color: @black-50; {% endhighlight %}Easily style your links with the right color with only one value.
{% highlight scss %} // Variables @link-color: @brand-primary; @link-color-hover: darken(@link-color, 15%); // Usage a { color: @link-color; text-decoration: none; &:hover { color: @link-color-hover; text-decoration: underline; } } {% endhighlight %}Note that the @link-color-hover 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 type face, text size, leading, and more with a few quick variables. Bootstrap makes use of these as well to provide easy typographic mixins.
{% highlight scss %} @font-family-sans-serif: "Helvetica Neue", Helvetica, Arial, sans-serif; @font-family-serif: Georgia, "Times New Roman", Times, serif; @font-family-monospace: Menlo, Monaco, Consolas, "Courier New", monospace; @font-family-base: @font-family-sans-serif; @font-size-base: 14px; @font-size-large: ceil((@font-size-base * 1.25)); // ~18px @font-size-small: ceil((@font-size-base * 0.85)); // ~12px @font-size-h1: floor((@font-size-base * 2.6)); // ~36px @font-size-h2: floor((@font-size-base * 2.15)); // ~30px @font-size-h3: ceil((@font-size-base * 1.7)); // ~24px @font-size-h4: ceil((@font-size-base * 1.25)); // ~18px @font-size-h5: @font-size-base; @font-size-h6: ceil((@font-size-base * 0.85)); // ~12px @line-height-base: 1.428571429; // 20/14 @line-height-computed: floor((@font-size-base * @line-height-base)); // ~20px @headings-font-family: inherit; @headings-font-weight: 500; @headings-line-height: 1.1; @headings-color: inherit; {% endhighlight %}Two quick variables for customizing the location and filename of your icons.
{% highlight scss %} @icon-font-path: "../fonts/"; @icon-font-name: "glyphicons-halflings-regular"; {% endhighlight %}Components throughout Bootstrap make use of some default variables for setting common values. Here are the most commonly used.
{% highlight scss %} @padding-base-vertical: 6px; @padding-base-horizontal: 12px; @padding-large-vertical: 10px; @padding-large-horizontal: 16px; @padding-small-vertical: 5px; @padding-small-horizontal: 10px; @padding-xs-vertical: 1px; @padding-xs-horizontal: 5px; @line-height-large: 1.33; @line-height-small: 1.5; @border-radius-base: 4px; @border-radius-large: 6px; @border-radius-small: 3px; @component-active-color: #fff; @component-active-bg: @brand-primary; @caret-width-base: 4px; @caret-width-large: 5px; {% endhighlight %}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.
{% highlight scss %} .box-sizing(@box-model) { -webkit-box-sizing: @box-model; // Safari <= 5 -moz-box-sizing: @box-model; // Firefox <= 19 box-sizing: @box-model; } {% endhighlight %}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.
{% highlight scss %} .transition(@transition) { -webkit-transition: @transition; transition: @transition; } .transition-property(@transition-property) { -webkit-transition-property: @transition-property; transition-property: @transition-property; } .transition-delay(@transition-delay) { -webkit-transition-delay: @transition-delay; transition-delay: @transition-delay; } .transition-duration(@transition-duration) { -webkit-transition-duration: @transition-duration; transition-duration: @transition-duration; } .transition-timing-function(@timing-function) { -webkit-transition-timing-function: @timing-function; transition-timing-function: @timing-function; } .transition-transform(@transition) { -webkit-transition: -webkit-transform @transition; -moz-transition: -moz-transform @transition; -o-transition: -o-transform @transition; transition: transform @transition; } {% endhighlight %}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.
{% highlight scss %} .rotate(@degrees) { -webkit-transform: rotate(@degrees); -ms-transform: rotate(@degrees); // IE9 only transform: rotate(@degrees); } .scale(@ratio; @ratio-y...) { -webkit-transform: scale(@ratio, @ratio-y); -ms-transform: scale(@ratio, @ratio-y); // IE9 only transform: scale(@ratio, @ratio-y); } .translate(@x; @y) { -webkit-transform: translate(@x, @y); -ms-transform: translate(@x, @y); // IE9 only transform: translate(@x, @y); } .skew(@x; @y) { -webkit-transform: skew(@x, @y); -ms-transform: skewX(@x) skewY(@y); // See https://github.com/twbs/bootstrap/issues/4885; IE9+ transform: skew(@x, @y); } .translate3d(@x; @y; @z) { -webkit-transform: translate3d(@x, @y, @z); transform: translate3d(@x, @y, @z); } .rotateX(@degrees) { -webkit-transform: rotateX(@degrees); -ms-transform: rotateX(@degrees); // IE9 only transform: rotateX(@degrees); } .rotateY(@degrees) { -webkit-transform: rotateY(@degrees); -ms-transform: rotateY(@degrees); // IE9 only transform: rotateY(@degrees); } .perspective(@perspective) { -webkit-perspective: @perspective; -moz-perspective: @perspective; perspective: @perspective; } .perspective-origin(@perspective) { -webkit-perspective-origin: @perspective; -moz-perspective-origin: @perspective; perspective-origin: @perspective; } .transform-origin(@origin) { -webkit-transform-origin: @origin; -moz-transform-origin: @origin; -ms-transform-origin: @origin; // IE9 only transform-origin: @origin; } {% endhighlight %}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.
{% highlight scss %} .animation(@animation) { -webkit-animation: @animation; animation: @animation; } .animation-name(@name) { -webkit-animation-name: @name; animation-name: @name; } .animation-duration(@duration) { -webkit-animation-duration: @duration; animation-duration: @duration; } .animation-timing-function(@timing-function) { -webkit-animation-timing-function: @timing-function; animation-timing-function: @timing-function; } .animation-delay(@delay) { -webkit-animation-delay: @delay; animation-delay: @delay; } .animation-iteration-count(@iteration-count) { -webkit-animation-iteration-count: @iteration-count; animation-iteration-count: @iteration-count; } .animation-direction(@direction) { -webkit-animation-direction: @direction; animation-direction: @direction; } {% endhighlight %}Set the opacity for all browsers and provide a filter fallback for IE8.
Provide context for form controls within each field.
{% highlight scss %} .placeholder(@color: @input-color-placeholder) { &::-moz-placeholder { color: @color; } // Firefox &:-ms-input-placeholder { color: @color; } // Internet Explorer 10+ &::-webkit-input-placeholder { color: @color; } // Safari and Chrome } {% endhighlight %}Generate columns via CSS within a single element.
{% highlight scss %} .content-columns(@width; @count; @gap) { -webkit-column-width: @width; -moz-column-width: @width; column-width: @width; -webkit-column-count: @count; -moz-column-count: @count; column-count: @count; -webkit-column-gap: @gap; -moz-column-gap: @gap; column-gap: @gap; } {% endhighlight %}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.
{% highlight scss %} #gradient > .vertical(#333; #000); #gradient > .horizontal(#333; #000); #gradient > .radial(#333; #000); {% endhighlight %}You can also specify the angle of a standard two-color, linear gradient:
{% highlight scss %} #gradient > .directional(#333; #000; 45deg); {% endhighlight %}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.
{% highlight scss %} #gradient > .striped(#333; 45deg); {% endhighlight %}Up the ante and use three colors instead. Set the first color, the second color, the second color's color stop (a decimal value like 0.25), and the third color with these mixins:
{% highlight scss %} #gradient > .vertical-three-colors(#777; #333; .25; #000); #gradient > .horizontal-three-colors(#777; #333; .25; #000); {% endhighlight %}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 Gallager.
Quickly center any element within its parent. Requires width or max-width to be set.
Specify the dimensions of an object more easily.
{% highlight scss %} // Mixins .size(@width; @height) { width: @width; height: @height; } .square(@size) { .size(@size; @size); } // Usage .image { .size(400px; 300px); } .avatar { .square(48px); } {% endhighlight %}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.
{% highlight scss %} .img-retina(@file-1x; @file-2x; @width-1x; @height-1x) { background-image: url("@{file-1x}"); @media only screen and (-webkit-min-device-pixel-ratio: 2), only screen and ( min--moz-device-pixel-ratio: 2), only screen and ( -o-min-device-pixel-ratio: 2/1), only screen and ( min-device-pixel-ratio: 2), only screen and ( min-resolution: 192dpi), only screen and ( min-resolution: 2dppx) { background-image: url("@{file-2x}"); background-size: @width-1x @height-1x; } } // Usage .jumbotron { .img-retina("/img/bg-1x.png", "/img/bg-2x.png", 100px, 100px); } {% endhighlight %}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.
As of Bootstrap 3.2, a right-to-left version of Bootstrap ships as part of the repository. It's powered by Twitter's CSS Flip project and is generated via our Gruntfile.
Bootstrap is by default a left-to-right project. For right-to-left projects, you'll need to set your language and replace the default Bootstrap CSS with an RTL version. First, set your language and text direction:
{% highlight html %} {% endhighlight %}Then, include the right-to-left CSS file in place of the default Bootstrap CSS:
{% highlight html %} {% endhighlight %}Alternatively, you may use the minified RTL file, bootstrap-rtl.min.css.
CSS Flip is a project for converting left-to-right CSS files into right-to-left CSS files. We use it in our Gruntfile to automate the generation of Bootstrap's RTL CSS files.