--- layout: page title: Reboot --- All of Bootstrap's element-specific CSS changes are part of what we call the Reboot, a single CSS file of simple overrides. 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 `` styles for a simpler baseline and later provide `.table`, `.table-bordered`, and more. ## Approach Here are our guidelines and reasons for choosing what to override in Reboot: - Use `rem`s and `em`s for units, nothing else. - Avoid `margin-top`. Vertical margins can collapse, yielding unexpected results. More importantly though, a single direction of `margin` is a simpler mental model. - For easier scaling across device sizes, block elements should use `rem`s for `margin`s. - Keep declarations of `font`-related properties to a minimal, using `inherit` whenever possible. ## Page defaults The `` and `` elements are updated to provide better page-wide defaults. More specifically: - The `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. - A base `font-size: 16px` is declared on the `` and `font-size: 1rem` on the `` for easy responsive type-scaling via media queryies. - The `` also sets a global `font-family` and `line-height`. This is inherited later by some form elements to prevent font inconsistencies. - For safety, the `` has a declared `background-color`, defaulting to `#fff`. ## Headings and paragraphs All heading elements—e.g., `

`—and `

` are reset to have their `margin-top` removed. Headings have `margin-bottom: .5rem` added and paragraphs `margin-bottom: 1rem` for easy spacing.

{% markdown %} # h1 heading Curabitur blandit tempus porttitor. Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. ## h2 heading Curabitur blandit tempus porttitor. Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. ### h3 heading Curabitur blandit tempus porttitor. Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. #### h4 heading Curabitur blandit tempus porttitor. Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. ##### h5 heading Curabitur blandit tempus porttitor. Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. ###### h6 heading Curabitur blandit tempus porttitor. Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. {% endmarkdown %}
## Lists All lists—`

`s and ensure consistent `text-align` throughout.
This is an example table, and this is it's caption to describe the contents.
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
## Code blocks The `
` element is reset to remove its `margin-top` and use `rem` units for its `margin-bottom`.



{% markdown %}

.element {
  margin-bottom: 1rem;
}


{% endmarkdown %}




## Inline elements



{% markdown %}
Praesent commodo cursus magna, vel scelerisque nisl consectetur et. For example, `
` should be wrapped as inline. Nulla attr vitae elit libero, a pharetra augue. Donec id elit non mi porta gravida at eget metus.
{% endmarkdown %}








Address




  Twitter, Inc.

  795 Folsom Ave, Suite 600

  San Francisco, CA 94107

  P: (123) 456-7890





  Full Name

  first.last@example.com







Blockquote




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

  
Someone famous in Source Title








Tables




  
    This is an example table, and this is it's caption to describe the contents.
  
  
    

      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
    

  







Forms




  

    Example legend