--- 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.
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>
.
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:
margin
on the bodybackground-color: white;
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, a project by Nicolas Gallagher and Jonathan Neal.
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 %}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.
Multiple device grids, columns, offsets, and column ordering.
Tiny grid Phones (<480px) | Small grid Tablets (<768px) | Medium-large grid Destkops (>768px) | |
---|---|---|---|
Grid behavior | Horizontal at all times | Collapsed to start, horizontal above breakpoints | |
Class prefix | .col- |
.col-sm- |
.col-lg- |
# of columns | 12 | ||
Nestable | Yes | ||
Offsets | N/A | Yes | |
Column ordering | N/A | Yes |
Bootstrap's grid system includes three levels of column sizing—phone, tablet, and desktop and up. Use each level in conjunction with the others for more control, or stick to the desktop classes for single-column, stacked mobile views.
On mobile devices, the grid starts out stacked. Above 768px, it becomes horizontal as media queries kick in to apply float
s and width
s. 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.
Be sure to checkout the full-page grid example as well.
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-lg-4
over four 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.
Easily change the order of our built-in grid columns with .col-push-*
and .col-pull-*
modifier classes.
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.
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 css %} @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 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 %}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 %}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 |
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.
...
{% 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.
...
{% 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.
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.
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.
Left aligned text.
Center aligned text.
Right aligned text.
{% endhighlight %}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.
...
...
...
...
{% 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 <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
{% endhighlight %}Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.
Someone famous Source Title
Use .pull-right
for a floated, right-aligned blockquote.
...{% 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 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.
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.
Wrap inline snippets of code with <code>
.
<section>
should be wrapped as inline.
<section>
should be wrapped as inline.
{% endhighlight %}
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 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 |
Add any of the following classes to the .table
base class.
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 IE8.
# | First Name | Last Name | Username |
---|---|---|---|
1 | Mark | Otto | @mdo |
2 | Jacob | Thornton | @fat |
3 | Larry | the Bird |
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 |
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.
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 |
Individual form controls automatically receive some global styling. All textual <input>
, <textarea>
, and <select>
elements are set to width: 100%;
by default.
Included with Bootstrap are optional form layouts for common use cases.
Add .form-inline
for left-aligned and inline-block controls for a compact layout.
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.
Use Bootstrap's predefined grid classes to align labels and groups of form controls in a horizontal layout.
{% highlight html %} {% endhighlight %}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.
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 .checkbox-inline
or .radio-inline
class to a series of checkboxes or radios for controls appear on the same line.
Use the default option or specify a multiple="multiple"
to show multiple options at once.
Provide feedback to users or visitors with basic feedback states on form controls and labels.
We remove the default outline
styles on some form controls and apply a box-shadow
in its place for :focus
.
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
.
Invalid inputs are styled via the :invalid
CSS selector, which is not supported by Internet Explorer 9 and below.
Add the disabled
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>
not impactedThis class will only change the appearance of <a class="btn btn-default">
buttons, not their functionality. Use custom JavaScript to disable links here.
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.
Bootstrap includes validation styles for error, warning, info, and success messages. To use:
.has-warning
, .has-error
, or .has-success
to the parent elementValidation styles are applied on a per-input basis. With horizontal forms, the <label class="control-label">
will always be styled.
Adding on top of existing browser controls, Bootstrap includes other useful form components.
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>
.
Avoid using <select>
elements here as they cannot be fully styled in WebKit browsers.
Add the relative form sizing classes to the `.input-group-addon`.
{% highlight html %}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.
Use relative sizing classes like .input-large
or match your inputs to the grid column sizes using .col-lg-*
classes.
Create larger or smaller form controls that match button sizes.
{% highlight html %} {% endhighlight %}Wrap inputs in grid columns, or any custom parent element, to easily enforce desired widths.
{% highlight html %}Block level help text for form controls.
{% highlight html %} A longer block of help text that breaks onto a new line and may extend beyond one line. {% endhighlight %}Use any of the available button classes to quickly create a styled button.
Fancy larger or smaller buttons? Add .btn-large
or .btn-small
for additional sizes.
{% endhighlight %}
Create block level buttons—those that span the full width of a parent— by adding .btn-block
.
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 will only change the <a>
's appearance, not its functionality. Use custom JavaScript to disable links here.
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.
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.
Use the generic close icon for dismissing content like modals and alerts.
Float an element left
{% highlight html %}Float an element right
{% highlight html %}Clear the float
on any element. Utilizes the micro clearfix as popularized by Nicolas Gallagher.
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.
Class | Small devices Up to 768px | Medium devices 768px to 979px | Large devices 980px and up |
---|---|---|---|
.visible-sm |
Visible | Hidden | Hidden |
.visible-md |
Hidden | Visible | Hidden |
.visible-lg |
Hidden | Hidden | Visible |
.hidden-sm |
Hidden | Visible | Visible |
.hidden-md |
Visible | Hidden | Visible |
.hidden-lg |
Visible | Visible | Hidden |
Class | Browser | |
---|---|---|
.visible-print |
Hidden | Visible |
.hidden-print |
Visible | Hidden |
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.
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 indicate the element is hidden in your current viewport.