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CSS Protips ★87749

A collection of tips to help take your CSS skills pro.

For other great lists check out @sindresorhus’s curated list of awesome lists ★87749.

Protips

Use a CSS Reset
Inherit box-sizing
Use unset Instead of Resetting All Properties
Use :not() to Apply/Unapply Borders on Navigation
Add line-height to body
Vertically-Center Anything
Comma-Separated Lists
Select Items Using Negative nth-child
Use SVG for Icons
Use the “Lobotomized Owl” Selector
Use max-height for Pure CSS Sliders
Equal-Width Table Cells
Get Rid of Margin Hacks With Flexbox
Use Attribute Selectors with Empty Links
Style “Default” Links
Consistent Vertical Rhythm
Intrinsic Ratio Boxes
Style Broken Images
Use rem for Global Sizing; Use em for Local Sizing
Hide Autoplay Videos That Aren’t Muted
Use :root for Flexible Type
Set font-size on Form Elements for a Better Mobile Experience
Use Pointer Events to Control Mouse Events

Use a CSS Reset

CSS resets help enforce style consistency across different browsers with a clean slate for styling elements. You can use a CSS reset library like Normalize, et al., or you can use a more simplified reset approach:

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

Now elements will be stripped of margins and padding, and box-sizing lets you manage layouts with the CSS box model.

Demo

Note: If you follow the Inherit box-sizing tip below you might opt to not include the box-sizing property in your CSS reset.

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Inherit `box-sizing`

Let box-sizing be inherited from html:

html {
  box-sizing: border-box;
}

*,
*::before,
*::after {
  box-sizing: inherit;
}

This makes it easier to change box-sizing in plugins or other components that leverage other behavior.

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Use `unset` Instead of Resetting All Properties

When resetting an element’s properties, it’s not necessary to reset each individual property:

button {
  background: none;
  border: none;
  color: inherit;
  font: inherit;
  outline: none;
  padding: 0;
}

You can specify all of an element’s properties using the all shorthand. Setting the value to unset changes an element’s properties to their initial values:

button {
  all: unset;
}

Note: the all shorthand isn’t supported in IE11 and is currently under consideration for support in Edge. unset isn’t supported in IE11.

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Use `:not()` to Apply/Unapply Borders on Navigation

Instead of putting on the border…

/* add border */
.nav li {
  border-right: 1px solid #666;
}

…and then taking it off the last element…

/* remove border */
.nav li:last-child {
  border-right: none;
}

…use the :not() pseudo-class to only apply to the elements you want:

.nav li:not(:last-child) {
  border-right: 1px solid #666;
}

Sure, you can use .nav li + li, but with :not() the intent is very clear and the CSS selector defines the border the way a human would describe it.

Demo

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Add `line-height` to `body`

You don’t need to add line-height to each <p>, <h*>, et al. separately. Instead, add it to body:

body {
  line-height: 1.5;
}

This way textual elements can inherit from body easily.

Demo

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Vertically-Center Anything

No, it’s not black magic, you really can center elements vertically. You can do this with flexbox…

html,
body {
  height: 100%;
  margin: 0;
}

body {
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
  display: -webkit-flex;
  display: flex;
}

…and also with CSS Grid:

body {
  display: grid;
  height: 100vh;
  margin: 0;
  place-items: center center;
}

Want to center something else? Vertically, horizontally…anything, anytime, anywhere? CSS-Tricks has a nice write-up on doing all of that.

Note: Watch for some buggy behavior ★9435 with flexbox in IE11.

Demo

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Comma-Separated Lists

Make list items look like a real, comma-separated list:

ul > li:not(:last-child)::after {
  content: ",";
}

Use the :not() pseudo-class and no comma will be added to the last item.

Note: This tip may not be ideal for accessibility, specifically screen readers. And copy/paste from the browser doesn’t work with CSS-generated content. Proceed with caution.

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Select Items Using Negative `nth-child`

Use negative nth-child in CSS to select items 1 through n.

li {
  display: none;
}

/* select items 1 through 3 and display them */
li:nth-child(-n+3) {
  display: block;
}

Or, since you’ve already learned a little about using :not(), try:

/* select all items except the first 3 and display them */
li:not(:nth-child(-n+3)) {
  display: block;
}

Demo

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Use SVG for Icons

There’s no reason not to use SVG for icons:

.logo {
  background: url("logo.svg");
}

SVG scales well for all resolution types and is supported in all browsers back to IE9. Ditch your .png, .jpg, or .gif-jif-whatev files.

Note: If you have SVG icon-only buttons for sighted users and the SVG fails to load, this will help maintain accessibility:

.no-svg .icon-only::after {
  content: attr(aria-label);
}

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Use the “Lobotomized Owl” Selector

It may have a strange name but using the universal selector (*) with the adjacent sibling selector (+) can provide a powerful CSS capability:

* + * {
  margin-top: 1.5em;
}

In this example, all elements in the flow of the document that follow other elements will receive margin-top: 1.5em.

For more on the “lobotomized owl” selector, read Heydon Pickering’s post on A List Apart.

Demo

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Use `max-height` for Pure CSS Sliders

Implement CSS-only sliders using max-height with overflow hidden:

.slider {
  max-height: 200px;
  overflow-y: hidden;
  width: 300px;
}

.slider:hover {
  max-height: 600px;
  overflow-y: scroll;
}

The element expands to the max-height value on hover and the slider displays as a result of the overflow.

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Equal-Width Table Cells

Tables can be a pain to work with. Try using table-layout: fixed to keep cells at equal width:

.calendar {
  table-layout: fixed;
}

Pain-free table layouts.

Demo

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Get Rid of Margin Hacks With Flexbox

When working with column gutters you can get rid of nth-, first-, and last-child hacks by using flexbox’s space-between property:

.list {
  display: flex;
  justify-content: space-between;
}

.list .person {
  flex-basis: 23%;
}

Now column gutters always appear evenly-spaced.

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Use Attribute Selectors with Empty Links

Display links when the <a> element has no text value but the href attribute has a link:

a[href^="http"]:empty::before {
  content: attr(href);
}

That’s pretty convenient.

Demo

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Style “Default” Links

Add a style for “default” links:

a[href]:not([class]) {
  color: #008000;
  text-decoration: underline;
}

Now links that are inserted via a CMS, which don’t usually have a class attribute, will have a distinction without generically affecting the cascade.

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Consistent Vertical Rhythm

Use a universal selector (*) within an element to create a consistent vertical rhythm:

.intro > * {
  margin-bottom: 1.25rem;
}

Consistent vertical rhythm provides a visual aesthetic that makes content far more readable.

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Intrinsic Ratio Boxes

To create a box with an intrinsic ratio, all you need to do is apply top or bottom padding to a div:

.container {
  height: 0;
  padding-bottom: 20%;
  position: relative;
}

.container div {
  border: 2px dashed #ddd;
  height: 100%;
  left: 0;
  position: absolute;
  top: 0;
  width: 100%;
}

Using 20% for padding makes the height of the box equal to 20% of its width. No matter the width of the viewport, the child div will keep its aspect ratio (100% / 20% = 5:1).

Demo

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Style Broken Images

Make broken images more aesthetically-pleasing with a little bit of CSS:

img {
  display: block;
  font-family: Helvetica, Arial, sans-serif;
  font-weight: 300;
  height: auto;
  line-height: 2;
  position: relative;
  text-align: center;
  width: 100%;
}

Now add pseudo-elements rules to display a user message and URL reference of the broken image:

img::before {
  content: "We're sorry, the image below is broken :(";
  display: block;
  margin-bottom: 10px;
}

img::after {
  content: "(url: " attr(src) ")";
  display: block;
  font-size: 12px;
}

Learn more about styling for this pattern in Ire Aderinokun’s original post.

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Use `rem` for Global Sizing; Use `em` for Local Sizing

After setting the base font size at the root (html { font-size: 100%; }), set the font size for textual elements to em:

h2 {
  font-size: 2em;
}

p {
  font-size: 1em;
}

Then set the font-size for modules to rem:

article {
  font-size: 1.25rem;
}

aside .module {
  font-size: .9rem;
}

Now each module becomes compartmentalized and easier to style, more maintainable, and flexible.

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Hide Autoplay Videos That Aren’t Muted

This is a great trick for a custom user stylesheet. Avoid overloading a user with sound from a video that autoplays when the page is loaded. If the sound isn’t muted, don’t show the video:

video[autoplay]:not([muted]) {
  display: none;
}

Once again, we’re taking advantage of using the :not() pseudo-class.

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Use `:root` for Flexible Type

The type font size in a responsive layout should be able to adjust with each viewport. You can calculate the font size based on the viewport height and width using :root:

:root {
  font-size: calc(1vw + 1vh + .5vmin);
}

Now you can utilize the root em unit based on the value calculated by :root:

body {
  font: 1rem/1.6 sans-serif;
}

Demo

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Set `font-size` on Form Elements for a Better Mobile Experience

To avoid mobile browsers (iOS Safari, et al.) from zooming in on HTML form elements when a <select> drop-down is tapped, add font-size to the selector rule:

input[type="text"],
input[type="number"],
select,
textarea {
  font-size: 16px;
}

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Use Pointer Events to Control Mouse Events

Pointer events allow you to specifiy how the mouse interacts with the element it’s touching. To disable the default pointer event on a button, for instance:

.button-disabled {
  opacity: .5;
  pointer-events: none;
}

It’s that simple.

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Support

Current versions of Chrome, Firefox, Safari, Opera, Edge, and IE11.

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Translations

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This list is a copy of AllThingsSmitty/css-protips with ranks

Ranked awesome lists, all in one place

CSS Protips ★87749

Table of Contents

Protips

Use a CSS Reset

Inherit box-sizing

Use unset Instead of Resetting All Properties

Use :not() to Apply/Unapply Borders on Navigation

Add line-height to body

Vertically-Center Anything

Comma-Separated Lists

Select Items Using Negative nth-child

Use SVG for Icons

Use the “Lobotomized Owl” Selector

Use max-height for Pure CSS Sliders

Equal-Width Table Cells

Get Rid of Margin Hacks With Flexbox

Use Attribute Selectors with Empty Links

Style “Default” Links

Consistent Vertical Rhythm

Intrinsic Ratio Boxes

Style Broken Images

Use rem for Global Sizing; Use em for Local Sizing

Hide Autoplay Videos That Aren’t Muted

Use :root for Flexible Type

Set font-size on Form Elements for a Better Mobile Experience

Use Pointer Events to Control Mouse Events

Support

Translations

Inherit `box-sizing`

Use `unset` Instead of Resetting All Properties

Use `:not()` to Apply/Unapply Borders on Navigation

Add `line-height` to `body`

Select Items Using Negative `nth-child`

Use `max-height` for Pure CSS Sliders

Use `rem` for Global Sizing; Use `em` for Local Sizing

Use `:root` for Flexible Type

Set `font-size` on Form Elements for a Better Mobile Experience