Preflight

Overview

Built on top of modern-normalize, Preflight is a set of base styles for Tailwind projects that are designed to smooth over cross-browser inconsistencies and make it easier for you to work within the constraints of your design system.

When you import tailwindcss into your project, Preflight is automatically injected into the base layer:

@layer theme, base, components, utilities;@import "tailwindcss/theme.css" layer(theme);@import "tailwindcss/preflight.css" layer(base);@import "tailwindcss/utilities.css" layer(utilities);

While most of the styles in Preflight are meant to go unnoticed—they simply make things behave more like you'd expect them to—some are more opinionated and can be surprising when you first encounter them.

For a complete reference of all the styles applied by Preflight, see the stylesheet.

Margins are removed

Preflight removes all of the default margins from all elements including headings, blockquotes, paragraphs, etc:

*,::after,::before,::backdrop,::file-selector-button {  margin: 0;  padding: 0;}

This makes it harder to accidentally rely on margin values applied by the user-agent stylesheet that are not part of your spacing scale.

Border styles are reset

In order to make it easy to add a border by simply adding the border class, Tailwind overrides the default border styles for all elements with the following rules:

*,::after,::before,::backdrop,::file-selector-button {  box-sizing: border-box;  border: 0 solid;}

Since the border class only sets the border-width property, this reset ensures that adding that class always adds a solid 1px border that uses currentColor.

This can cause some unexpected results when integrating certain third-party libraries, like Google maps for example.

When you run into situations like this, you can work around them by overriding the Preflight styles with your own custom CSS:

@layer base {  .google-map * {    border-style: none;  }}

Headings are unstyled

All heading elements are completely unstyled by default, and have the same font size and weight as normal text:

h1,h2,h3,h4,h5,h6 {  font-size: inherit;  font-weight: inherit;}

The reason for this is two-fold:

• It helps you avoid accidentally deviating from your type scale. By default, browsers assign sizes to headings that don't exist in Tailwind's default type scale, and aren't guaranteed to exist in your own type scale.
• In UI development, headings should often be visually de-emphasized. Making headings unstyled by default means any styling you apply to headings happens consciously and deliberately.

You can always add default header styles to your project by adding your own base styles.

Lists are unstyled

Ordered and unordered lists are unstyled by default, with no bullets or numbers:

ol,ul,menu {  list-style: none;}

If you'd like to style a list, you can do so using the list-style-type and list-style-position utilities:

<ul class="list-inside list-disc">  <li>One</li>  <li>Two</li>  <li>Three</li></ul>

You can always add default list styles to your project by adding your own base styles.

Accessibility considerations

Unstyled lists are not announced as lists by VoiceOver. If your content is truly a list but you would like to keep it unstyled, add a "list" role to the element:

<ul role="list">  <li>One</li>  <li>Two</li>  <li>Three</li></ul>

Images are block-level

Images and other replaced elements (like svg, video, canvas, and others) are display: block by default:

img,svg,video,canvas,audio,iframe,embed,object {  display: block;  vertical-align: middle;}

This helps to avoid unexpected alignment issues that you often run into using the browser default of display: inline.

If you ever need to make one of these elements inline instead of block, simply use the inline utility:

<img class="inline" src="..." alt="..." />

Images are constrained

Images and videos are constrained to the parent width in a way that preserves their intrinsic aspect ratio:

img,video {  max-width: 100%;  height: auto;}

This prevents them from overflowing their containers and makes them responsive by default. If you ever need to override this behavior, use the max-w-none utility:

<img class="max-w-none" src="..." alt="..." />

Extending Preflight

If you'd like to add your own base styles on top of Preflight, add them to the base CSS layer in your CSS using @layer base:

@layer base {  h1 {    font-size: var(--text-2xl);  }  h2 {    font-size: var(--text-xl);  }  h3 {    font-size: var(--text-lg);  }  a {    color: var(--color-blue-600);    text-decoration-line: underline;  }}

Learn more in the adding base styles documentation.

Disabling Preflight

If you'd like to completely disable Preflight—perhaps because you're integrating Tailwind into an existing project or you'd prefer to define your own base styles—you can do so by importing only the parts of Tailwind that you need.

By default, this is what @import "tailwindcss"; injects:

@layer theme, base, components, utilities;@import "tailwindcss/theme.css" layer(theme);@import "tailwindcss/preflight.css" layer(base);@import "tailwindcss/utilities.css" layer(utilities);

To disable Preflight, simply omit its import while keeping everything else:

@layer theme, base, components, utilities;@import "tailwindcss/theme.css" layer(theme);@import "tailwindcss/preflight.css" layer(base);@import "tailwindcss/utilities.css" layer(utilities);