layout: docs title: Reboot group: content
Part of Bootstrap's job is to provide an elegant, consistent, and simple baseline to build upon. We use Reboot, a collection of element-specific CSS changes in a single file, to kickstart that.
Reboot builds upon Normalize, providing many HTML elements with somewhat opinionated styles using only element selectors. Additional styling is done only with classes. For example, we reboot some <table>
styles for a simpler baseline and later provide .table
, .table-bordered
, and more.
Here are our guidelines and reasons for choosing what to override in Reboot:
rem
s instead of em
s for scalable component spacing.margin-top
. Vertical margins can collapse, yielding unexpected results. More importantly though, a single direction of margin
is a simpler mental model.rem
s for margin
s.font
-related properties to a minimal, using inherit
whenever possible.The <html>
and <body>
elements are updated to provide better page-wide defaults. More specifically:
box-sizing
is globally set on every element—including *:before
and *after
, to border-box
. This ensures that the declared width of element is never exceeded due to padding or border.font-size: 16px
is declared on the <html>
and font-size: 1rem
on the <body>
for easy responsive type-scaling via media queryies.<body>
also sets a global font-family
and line-height
. This is inherited later by some form elements to prevent font inconsistencies.<body>
has a declared background-color
, defaulting to #fff
.All heading elements—e.g., <h1>
—and <p>
are reset to have their margin-top
removed. Headings have margin-bottom: .5rem
added and paragraphs margin-bottom: 1rem
for easy spacing.
All lists—<ul>
, <ol>
, and <dl>
—have their margin-top
removed and a margin-bottom: 1rem
. Nested lists have no margin-bottom
.
For simpler styling, clear hierarchy, and better spacing, description lists have updated margin
s. <dd>
s reset margin-left
to 0
and add margin-bottom: .5rem
. <dt>
s are bolded.
The <pre>
element is reset to remove its margin-top
and use rem
units for its margin-bottom
.
.element { margin-bottom: 1rem; }{% endmarkdown %}
Tables are slightly adjusted to style <caption>
s and ensure consistent text-align
throughout. Additional changes for borders, padding, and more come with the .table
class.
Table heading | Table heading | Table heading | Table heading |
---|---|---|---|
Table cell | Table cell | Table cell | Table cell |
Table cell | Table cell | Table cell | Table cell |
Table cell | Table cell | Table cell | Table cell |
Various form elements have been rebooted for simpler base styles. Here are some of the most notable changes:
<fieldset>
s have no borders, padding, or margin so they can be easily used as wrappers for individual inputs or groups of inputs.<legend>
s, like fieldsets, have also been restyled to be displayed as a heading of sorts.<label>
s are set to display: inline-block
to allow margin
to be applied.<input>
s, <selects>
s, <textareas>
s, and <buttons>
s are mostly addressed by Normalize, but Reboot removes their margin
and sets line-height: inherit
, too.<textarea>
s are modified to only be resizeble vertically as horizontal resizing often "breaks" page layout.These changes, and more, are demonstrated below.
Example legendExample input
Example select Choose... Option 1 Option 2 Option 3 Option 4 Option 5 Option 6
Check this checkbox
Option one is this and that Option two is something else that's also super long to demonstrate the wrapping of these fancy form controls. Option three is disabled
Example textarea
Example temporal
Example output 100
Button submit
Button submit
The <address>
element is updated to reset the browser default font-style
from italic
to normal
. line-height
is also now inherited, and margin-bottom: 1rem
has been added. <address>
s are for presenting contact information for the nearest ancestor (or an entire body of work). Preserve formatting by ending lines with <br>
.
The default margin
on blockquotes is 1em 40px
, so we reset that to 0 0 1rem
for something more consistent with other elements.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.
Someone famous in Source Title
The <abbr>
element receives basic styling to make it stand the amongst paragraph text.