--- layout: default title: CSS slug: css lead: "Fundamental HTML elements styled and enhanced with extensible classes." ---

Get the lowdown on the key pieces of Bootstrap's infrastructure, including our approach to better, faster, stronger web development.

HTML5 doctype required

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 %}

Mobile first

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>.

{% highlight html %} {% endhighlight %}

Responsive images

We automatically attempt to scale images to appropriate sizes with a global max-width: 100%; on all <img> elements. If you run into problems (e.g., with Google Maps), be sure to disable this property on a per-case basis.

Bootstrap sets basic global display, typography, and link styles. Specifically, we:

These styles can be found within scaffolding.less.

Normalize reset

For improved cross-browser rendering, we use Normalize, a project by Nicolas Gallagher and Jonathan Neal.

Centering with container

Easily center a page's contents by wrapping its contents in a container. Containers set `max-width` at various media query breakpoints to match our grid system.

{% highlight html %}
...
{% endhighlight %}

Bootstrap includes a responsive, percent-based grid system that appropriately scales up to 12 columns as the device or viewport size increases—in other words, it's mobile first. It includes predefined classes for this, as well as powerful mixins for generating semantic layouts.

Grid example

On mobile devices, the grid starts out stacked. Above 768px, it becomes horizontal as media queries kick in to apply floats and widths. To create a basic grid layout, wrap a series of .col-lg-* elements within a .row. As this is a 12-column grid, each .col-lg-* spans a number of those 12 columns, and should always add up to 12 for each row (or the number of columns in the parent), even at mobile resolutions.

1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
6
6
{% highlight html %}
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
6
6
{% endhighlight %}

Offsetting columns

Move columns to the right using .col-offset-* classes. These classes increase the left margin of a column by * columns. For example, .col-offset-4 moves .col col-lg-4 over four columns.

4
4 offset 4
3 offset 3
3 offset 3
6 offset 3
{% highlight html %}
...
...
3 offset 3
3 offset 3
...
{% endhighlight %}

Nesting columns

To nest your content with the default grid, add a new .row and set of .col-lg-* columns within an existing .col-lg-* column. Nested rows should include a set of columns that add up to 12.

Level 1: 9 columns
Level 2: 6 columns
Level 2: 6 columns
{% highlight html %}
Level 1: 9 columns
Level 2: 6 columns
Level 2: 6 columns
{% endhighlight %}

Column ordering

Easily change the order of our built-in grid columns with .col-push-* and .col-pull-* modifier classes.

9
3
{% highlight html %}
9
3
{% endhighlight %}

Small device grid

Use the small device grid classes, like .col-sm-6, to create columned layouts on phone and tablet devices (anything under 768px). Offsets, pushes, and pulls are not available with the small grid at this time.

4 cols, 6 small cols
4 cols, 6 small cols
4 cols, 12 small cols
{% highlight html %}
4 cols, 6 small cols
4 cols, 6 small cols
4 cols, 12 small cols
{% endhighlight %}

LESS mixins and variables

In addition to prebuilt grid classes for fast layouts, Bootstrap includes LESS variables and mixins for quickly generating your own simple, semantic layouts.

Variables

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 css %} @grid-columns: 12; @grid-gutter-width: 30px; @grid-float-breakpoint: 768px; {% endhighlight %}

Mixins

Mixins are used in conjunction with the grid variables to generate semantic CSS for individual grid columns.

{% highlight css %} // Creates a wrapper for a series of columns .make-row() { // Negative margin the row out to align the content of columns margin-left: (@grid-gutter-width / -2); margin-right: (@grid-gutter-width / -2); // Then clear the floated columns .clearfix(); } // Generate the columns .make-column(@columns) { @media (min-width: @grid-float-breakpoint) { float: left; // Calculate width based on number of columns available width: percentage(@columns / @grid-columns); } // Prevent columns from collapsing when empty min-height: 1px; // Set inner padding as gutters instead of margin padding-left: (@grid-gutter-width / 2); padding-right: (@grid-gutter-width / 2); } // Generate the column offsets .make-column-offset(@columns) { @media (min-width: @grid-float-breakpoint) { margin-left: percentage((@columns / @grid-columns)); } } {% endhighlight %}

Example usage

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 css %} .wrapper { .make-row(); } .content-main { .make-column(8); } .content-secondary { .make-column(3); .make-column-offset(1); } {% endhighlight %} {% highlight html %}
...
...
{% endhighlight %}

Headings

All HTML headings, <h1> through <h6> are available.

Bootstrap heading

Semibold 38px

Bootstrap heading

Semibold 32px

Bootstrap heading

Semibold 24px

Bootstrap heading

Semibold 18px
Bootstrap heading
Semibold 16px
Bootstrap heading
Semibold 12px
{% highlight html %}

...

...

...

...

...
...
{% endhighlight %}

Body copy

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.

{% highlight html %}

...

{% endhighlight %}

Lead body copy

Make a paragraph stand out by adding .lead.

Vivamus sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Duis mollis, est non commodo luctus.

{% highlight html %}

...

{% endhighlight %}

Built with Less

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.

Emphasis

Make use of HTML's default emphasis tags with lightweight styles.

Small text

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.

This line of text is meant to be treated as fine print.

{% highlight html %} This line of text is meant to be treated as fine print. {% endhighlight %}

Bold

For emphasizing a snippet of text with a heavier font-weight.

The following snippet of text is rendered as bold text.

{% highlight html %} rendered as bold text {% endhighlight %}

Italics

For emphasizing a snippet of text with italics.

The following snippet of text is rendered as italicized text.

{% highlight html %} rendered as italicized text {% endhighlight %}

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.

Alignment classes

Easily realign text to components with text alignment classes.

Left aligned text.

Center aligned text.

Right aligned text.

{% highlight html %}

Left aligned text.

Center aligned text.

Right aligned text.

{% endhighlight %}

Emphasis classes

Convey meaning through color with a handful of emphasis utility classes.

Fusce dapibus, tellus ac cursus commodo, tortor mauris nibh.

Etiam porta sem malesuada magna mollis euismod.

Donec ullamcorper nulla non metus auctor fringilla.

Duis mollis, est non commodo luctus, nisi erat porttitor ligula.

{% highlight html %}

...

...

...

...

{% endhighlight %}

Abbreviations

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.

Basic abbreviation

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.

{% highlight html %} attr {% endhighlight %}

Initialism

Add .initialism to an abbreviation for a slightly smaller font-size.

HTML is the best thing since sliced bread.

{% highlight html %} HTML {% endhighlight %}

Addresses

Present contact information for the nearest ancestor or the entire body of work. Preserve formatting by ending all lines with <br>.

Twitter, Inc.
795 Folsom Ave, Suite 600
San Francisco, CA 94107
P: (123) 456-7890
Full Name
first.last@example.com
{% highlight html %}
Twitter, Inc.
795 Folsom Ave, Suite 600
San Francisco, CA 94107
P: (123) 456-7890
Full Name
first.last@example.com
{% endhighlight %}

Blockquotes

For quoting blocks of content from another source within your document.

Default blockquote

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.

{% highlight html %}

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.

{% endhighlight %}

Blockquote options

Style and content changes for simple variations on a standard blockquote.

Naming a source

Add <small> tag 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.

Someone famous in Source Title
{% highlight html %}

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.

Someone famous Source Title
{% endhighlight %}

Alternate displays

Use .pull-right for a floated, right-aligned blockquote.

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.

Someone famous in Source Title
{% highlight html %}
...
{% endhighlight %}

Lists

Unordered

A list of items in which the order does not explicitly matter.

{% highlight html %} {% endhighlight %}

Ordered

A list of items in which the order does explicitly matter.

  1. Lorem ipsum dolor sit amet
  2. Consectetur adipiscing elit
  3. Integer molestie lorem at massa
  4. Facilisis in pretium nisl aliquet
  5. Nulla volutpat aliquam velit
  6. Faucibus porta lacus fringilla vel
  7. Aenean sit amet erat nunc
  8. Eget porttitor lorem
{% highlight html %}
  1. ...
{% endhighlight %}

Unstyled

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.

{% highlight html %} {% endhighlight %}

Inline

Place all list items on a single line with inline-block and some light padding.

{% highlight html %} {% endhighlight %}

Description

A list of terms with their associated descriptions.

Description lists
A description list is perfect for defining terms.
Euismod
Vestibulum id ligula porta felis euismod semper eget lacinia odio sem nec elit.
Donec id elit non mi porta gravida at eget metus.
Malesuada porta
Etiam porta sem malesuada magna mollis euismod.
{% highlight html %}
...
...
{% endhighlight %}

Horizontal description

Make terms and descriptions in <dl> line up side-by-side.

Description lists
A description list is perfect for defining terms.
Euismod
Vestibulum id ligula porta felis euismod semper eget lacinia odio sem nec elit.
Donec id elit non mi porta gravida at eget metus.
Malesuada porta
Etiam porta sem malesuada magna mollis euismod.
Felis euismod semper eget lacinia
Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.
{% highlight html %}
...
...
{% endhighlight %}
Auto-truncating

Horizontal description lists will truncate terms that are too long to fit in the left column fix text-overflow. In narrower viewports, they will change to the default stacked layout.

Inline

Wrap inline snippets of code with <code>.

For example, <section> should be wrapped as inline.
{% highlight html %} For example, <section> should be wrapped as inline. {% endhighlight %}

Basic block

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>
{% highlight html %}
<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.

Basic example

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 @twitter
{% highlight html %} ...
{% endhighlight %}

Optional classes

Add any of the following classes to the .table base class.

Striped

Use .table-striped to add zebra-striping to any table row within the <tbody>.

Cross-browser compatibility

Striped tables are styled via the :nth-child CSS selector, which is not available in IE8.

# First Name Last Name Username
1 Mark Otto @mdo
2 Jacob Thornton @fat
3 Larry the Bird @twitter
{% highlight html %} ...
{% endhighlight %}

Bordered

Add .table-bordered for borders and rounded corners.

# First Name Last Name Username
1 Mark Otto @mdo
Mark Otto @TwBootstrap
2 Jacob Thornton @fat
3 Larry the Bird @twitter
{% highlight html %} ...
{% endhighlight %}

Hover rows

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 @twitter
{% highlight html %} ...
{% endhighlight %}

Condensed

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 @twitter
{% highlight html %} ...
{% endhighlight %}

Optional row classes

Use contextual classes to color table rows.

Class Description
.success Indicates a successful or positive action.
.danger Indicates a dangerous or potentially negative action.
.warning Indicates a warning that might need attention.
.info Used as an alternative to the default styles.
# Product Payment Taken Status
1 TB - Monthly 01/04/2012 Approved
2 TB - Monthly 02/04/2012 Declined
3 TB - Monthly 03/04/2012 Pending
{% highlight html %} ... 1 TB - Monthly 01/04/2012 Approved ... {% endhighlight %}

Basic example

Individual form controls automatically receive some global styling. All textual <input>, <textarea>, and <select> elements are set to width: 100%; by default.

Legend

Example block-level help text here.

{% highlight html %}
Legend

Example block-level help text here.

{% endhighlight %}

Optional layouts

Included with Bootstrap are optional form layouts for common use cases.

Inline form

Add .form-inline for left-aligned and inline-block controls for a compact layout.

Requires custom widths

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.

{% highlight html %}
{% endhighlight %}

Horizontal form

Use Bootstrap's predefined grid classes to align labels and groups of form controls in a horizontal layout.

{% highlight html %}
{% endhighlight %}

Supported form controls

Examples of standard form controls supported in an example form layout.

Inputs

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.

Type declaration required

Inputs will only be fully styled if their type is properly declared.

{% highlight html %} {% endhighlight %}

Textarea

Form control which supports multiple lines of text. Change rows attribute as necessary.

{% highlight html %} {% endhighlight %}

Checkboxes and radios

Checkboxes are for selecting one or several options in a list while radios are for selecting one option from many.

Default (stacked)


{% highlight html %}
{% endhighlight %}

Inline checkboxes

Use .checkbox-inline or .radio-inline class to a series of checkboxes or radios for controls appear on the same line.

{% highlight html %} {% endhighlight %}

Selects

Use the default option or specify a multiple="multiple" to show multiple options at once.


{% highlight html %} {% endhighlight %}

Form control states

Provide feedback to users or visitors with basic feedback states on form controls and labels.

Input focus

We remove the default outline styles on some form controls and apply a box-shadow in its place for :focus.

{% highlight html %} {% endhighlight %}

Invalid inputs

Style inputs via default browser functionality. Specify a type, add the required attribute if the field is not optional, and (if applicable) specify a pattern.

Cross-browser compatibility

Invalid inputs are styled via the :invalid CSS selector, which is not supported by Internet Explorer 9 and below.

{% highlight html %} {% endhighlight %}

Disabled inputs

Add the disabled attribute on an input to prevent user input and trigger a slightly different look.

{% highlight html %} {% endhighlight %}

Disabled fieldsets

Add the disabled attribute to a <fieldset> to disable all the controls within the <fieldset> at once.

Link functionality of <a> not impacted

This class will only change the appearance of <a class="btn btn-default"> buttons, not their functionality. Use custom JavaScript to disable links here.

Cross-browser compatibility

While Bootstrap will apply these styles in all browsers, IE and Safari don't actually support the <disabled> attribute on a <fieldset>. Use custom JavaScript to disable the fieldset in these browsers.

{% highlight html %}
{% endhighlight %}

Validation states

Bootstrap includes validation styles for error, warning, info, and success messages. To use:

Validation styles are applied on a per-input basis. With horizontal forms, the <label class="control-label"> will always be styled.

{% highlight html %}
{% endhighlight %}

Extending form controls

Adding on top of existing browser controls, Bootstrap includes other useful form components.

Input groups

Add text or buttons before, after, or on both sides of any text-based input. Use .input-group with a .add-on to prepend or append elements to an <input>.

Cross-browser compatibility

Avoid using <select> elements here as they cannot be fully styled in WebKit browsers.

@

.00

$ .00
{% highlight html %}
@
.00
$ .00
{% endhighlight %}

Optional sizes

Add the relative form sizing classes to the `.input-group-addon`.

@

@

@
{% highlight html %}
@
@
@
{% endhighlight %}

Buttons instead of text

Buttons in input groups are a bit different and require one extra level of nesting. Instead of .input-group-addon, you'll need to use .input-group-btn to wrap the buttons. This is required due to default browser styles that cannot be overridden.


{% highlight html %}
{% endhighlight %}

Button dropdowns


{% highlight html %}
{% endhighlight %}

Segmented dropdown groups


{% highlight html %}
{% endhighlight %}

Control sizing

Use relative sizing classes like .input-large or match your inputs to the grid column sizes using .col-lg-* classes.

Relative sizing

Create larger or smaller form controls that match button sizes.

{% highlight html %} {% endhighlight %}

Column sizing

Wrap inputs in grid columns, or any custom parent element, to easily enforce desired widths.

{% highlight html %}
{% endhighlight %}

Help text

Block level help text for form controls.

A longer block of help text that breaks onto a new line and may extend beyond one line.
{% highlight html %} A longer block of help text that breaks onto a new line and may extend beyond one line. {% endhighlight %}

Button options

Use any of the available button classes to quickly create a styled button.

{% highlight html %} {% endhighlight %}

Button sizes

Fancy larger or smaller buttons? Add .btn-large or .btn-small for additional sizes.

{% highlight html %}

{% endhighlight %}

Create block level buttons—those that span the full width of a parent— by adding .btn-block.

{% highlight html %} {% endhighlight %}

Disabled state

Make buttons look unclickable by fading them back 50%.

Button element

Add the disabled attribute to <button> buttons.

{% highlight html %} {% endhighlight %}

Cross-browser compatibility

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.

Anchor element

Add the .disabled class to <a> buttons.

Primary link Link

{% highlight html %} Primary link Link {% endhighlight %}

We use .disabled as a utility class here, similar to the common .active class, so no prefix is required.

Link functionality not impacted

This class will only change the <a>'s appearance, not its functionality. Use custom JavaScript to disable links here.

Using multiple tags

Use the button classes on an <a>, <button>, or <input> element.

Link
{% highlight html %} Link {% endhighlight %}

Cross-browser rendering

As a best practice, we highly recommend using the <button> element whenever possible to ensure matching cross-browser rendering.

Add classes to an <img> element to easily style images in any project.

Cross-browser compatibility

Keep in mind that Internet Explorer 8 lacks support for rounded corners.

{% highlight html %} {% endhighlight %}

Close icon

Use the generic close icon for dismissing content like modals and alerts.

{% highlight html %} {% endhighlight %}

.pull-left

Float an element left

{% highlight html %}
...
{% endhighlight %} {% highlight css %} .pull-left { float: left; } {% endhighlight %}

.pull-right

Float an element right

{% highlight html %}
...
{% endhighlight %} {% highlight css %} .pull-right { float: right; } {% endhighlight %}

.clearfix

Clear the float on any element. Utilizes the micro clearfix as popularized by Nicolas Gallagher.

{% highlight html %}
...
{% endhighlight %} {% highlight css %} // Mixin .clearfix { &:before, &:after { content: " "; display: table; } &:after { clear: both; } } // Usage .element { .clearfix(); } {% endhighlight %}

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.

Responsive classes

Print classes

Class Browser Print
.visible-print Visible
.hidden-print Visible

When to use

Use on a limited basis and avoid creating entirely different versions of the same site. Instead, use them to complement each device's presentation. Responsive utilities are currently only available for block-level toggling, meaning display: none; or display: block;. Use with inline and table elements is currently not supported.

Test case

Resize your browser or load on different devices to test the responsive utility classes.

Visible on...

Green checkmarks indicate the element is visible in your current viewport.

Hidden on...

Here, green checkmarks indicate the element is hidden in your current viewport.