Reboot CSS

Reboot is a collection of element-specific CSS changes in a single file to help kickstart building a site with the Fluent UI Blazor library. It provides an elegant, consistent, and simple baseline to build upon (inspired by Bootstrap's Reboot which again is based on Normalize.css)

If you want to use Reboot, like this demo site, you'll need to include it in your App.razor or index.html file like this: 

<link href="/_content/Microsoft.FluentUI.AspNetCore.Components/css/reboot.css" rel="stylesheet" />
If you are creating a site by using our Templates package, this is already set up for you. You can download the file to see what's inside.

PS: It is entirely possible to build a site without using Reboot but you will have to do more styling yourself.

PSs: When creating a site that is hosted in a different base path,it might be necessary to remove the leading '/' from the stylesheet link.

Approach

Reboot builds upon Bootstrap's Reboot which itself builds upon Normalize, providing many HTML elements with somewhat opinionated styles using only element selectors.

Here are our guidelines and reasons for choosing what to override in Reboot:

  • Update some browser default values to use rems instead of ems for scalable component spacing.
  • 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 rems for margins.
  • Keep declarations of font-related properties to a minimum, using inherit whenever possible.

Page defaults

The <html> and <body> 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.
    • No base font-size is declared on the <html>, but --type-ramp-base-font-size: 14px; is assumed (the Fluent UI default). font-size: var(--type-ramp-base-font-size) is applied on the <body> and can be overridden by modifying the --type-ramp-base-font-size variable.
  • The <body> also sets a global font-family (var(--body-font)), font-weight (var(--font-weight)), line-height (var(--type-ramp-base-font-size)), and color (var(--neutral-base-color);). This is inherited later by some form elements to prevent font inconsistencies.
  • For safety, the <body> has a declared background-color, defaulting to var(--neutral-fill-layer-rest).

Headings and paragraphs

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.

Heading Example
<h1></h1>

h1. Fluent UI heading

<h2></h2>

h2. Fluent UI heading

<h3></h3>

h3. Fluent UI heading

<h4></h4>

h4. Fluent UI heading

<h5></h5>

h5. Fluent UI heading

<h6></h6>
h6. Fluent UI heading

Lists

All lists—<ul>, <ol>, and <dl>—have their margin-top removed and a margin-bottom: 1rem. Nested lists have no margin-bottom. We’ve also reset the padding-left on <ul> and <ol> elements.

  • All lists have their top margin removed
  • And their bottom margin normalized
  • Nested lists have no bottom margin
    • This way they have a more even appearance
    • Particularly when followed by more list items
  • The left padding has also been reset
  1. Here’s an ordered list
  2. With a few list items
  3. It has the same overall look
  4. As the previous unordered list

For simpler styling, clear hierarchy, and better spacing, description lists have updated margins. <dd>s reset margin-left to 0 and add margin-bottom: .5rem. <dt>s are bolded.

Description lists
A description list is perfect for defining terms.
Term
Definition for the term.
A second definition for the same term.
Another term
Definition for this other term.

Inline code

Wrap inline snippets of code with <code>. Be sure to escape HTML angle brackets.

For example, <section> should be wrapped as inline.

Code blocks

Use <pre>s for multiple lines of code. Once again, be sure to escape any angle brackets in the code for proper rendering. The <pre> element is reset to remove its margin-top and use rem units for its margin-bottom.

<p>Sample text here...</p>
<p>And another line of sample text here...</p>

Variables

For indicating variables use the <var> tag.

y = mx + b

User input

Use the <kbd> to indicate input that is typically entered via keyboard.

To switch directories, type cd followed by the name of the directory.
To edit settings, press ctrl + ,

Sample output

For indicating sample output from a program use the <samp> tag.

This text is meant to be treated as sample output from a computer program.

Tables

Tables are slightly adjusted to style <caption>s, collapse borders, and ensure consistent text-align throughout. Additional changes for borders, padding, and more come with the .table class.

This is an example table, and this is its 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

To maintain a consistent look and feel, we stongly advise you to use the Fluent Input components as described in the Form & inputs section. It is however also still possible of course to use the standard HTML input components. Most of them 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, <select>s, <textarea>s, and <button>s are mostly addressed by Normalize, but Reboot removes their margin and sets line-height: inherit, too.
  • <textarea>s are modified to only be resizable vertically as horizontal resizing often “breaks” page layout.
  • <button>s and <input> button elements have cursor: pointer when :not(:disabled).

These changes, and more, are demonstrated below.

Example legend

100

Date & color input support

Keep in mind date inputs are not fully supported by all browsers, namely Safari.

Pointers on buttons

Reboot includes an enhancement for role="button" to change the default cursor to pointer. Add this attribute to elements to help indicate elements are interactive. This role isn’t necessary for <button> elements, which get their own cursor change.

Non-button element button

Misc elements

Address

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>.

Microsoft Corporation
1 Microsoft Way
Redmond, WA 98052
P: (425) 882-8080
Full Name
first.last@example.com

Blockquote

The default margin on blockquotes is 1em 40px.

A well-known quote, contained in a blockquote element.

Someone famous in Source Title

Inline elements

The <abbr> element receives basic styling to make it stand out amongst paragraph text.

The HTML abbreviation element.

Summary

The default cursor on summary is text, so we reset that to pointer to convey that the element can be interacted with by clicking on it.

Some details

More info about the details.

Even more details

Here are even more details about the details.

HTML5 [hidden] attribute

HTML5 adds a new global attribute named [hidden], which is styled as display: none by default. Borrowing an idea from PureCSS, we improve upon this default by making [hidden] { display: none !important; } to help prevent its display from getting accidentally overridden.

<input type="text" hidden>
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