CSS Pseudo-Classes

Master CSS pseudo-classes to style elements based on their state, position, and user interaction for dynamic styling.

Pseudo-classes select elements based on their state or position. They're essential for creating interactive, dynamic interfaces.

Common Pseudo-Classes

Link States

a:link {
  color: #007bff; /* Unvisited */
}

a:visited {
  color: #6610f2; /* Visited */
}

a:hover {
  color: #0056b3; /* Mouse over */
}

a:active {
  color: #ff3300; /* Being clicked */
}

Focus

input:focus {
  outline: 2px solid #007bff;
  border-color: #007bff;
}

button:focus-visible {
  outline: 3px solid #007bff;
  outline-offset: 2px;
}

.element:focus-within {
  /* When any child has focus */
  border-color: #007bff;
}

Structural Pseudo-Classes

First and Last

li:first-child {
  font-weight: bold;
}

li:last-child {
  border-bottom: none;
}

p:first-of-type {
  font-size: 1.2em;
}

p:last-of-type {
  margin-bottom: 0;
}

Nth Child

/* Even rows */
tr:nth-child(even) {
  background-color: #f8f9fa;
}

/* Odd rows */
tr:nth-child(odd) {
  background-color: white;
}

/* Every third item */
li:nth-child(3n) {
  color: #007bff;
}

/* First 3 items */
li:nth-child(-n+3) {
  font-weight: bold;
}

/* All but first 3 */
li:nth-child(n+4) {
  opacity: 0.7;
}

Nth of Type

p:nth-of-type(2) {
  color: #007bff;
}

div:nth-of-type(odd) {
  background-color: #f8f9fa;
}

Only Child

li:only-child {
  list-style: none;
}

p:only-of-type {
  text-align: center;
}

User Action Pseudo-Classes

Hover

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

button:hover {
  background-color: #0056b3;
}

Active

button:active {
  transform: scale(0.95);
}

.link:active {
  color: #ff3300;
}

Focus

input:focus {
  border-color: #007bff;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.3);
}

Input Pseudo-Classes

Enabled and Disabled

input:enabled {
  background-color: white;
}

input:disabled {
  background-color: #e9ecef;
  cursor: not-allowed;
  opacity: 0.6;
}

Checked

input[type="checkbox"]:checked {
  background-color: #007bff;
}

input[type="radio"]:checked + label {
  font-weight: bold;
  color: #007bff;
}

Valid and Invalid

input:valid {
  border-color: #28a745;
}

input:invalid {
  border-color: #dc3545;
}

input:required {
  border-left: 3px solid #007bff;
}

input:optional {
  border-left: 3px solid #6c757d;
}

In Range and Out of Range

input:in-range {
  border-color: #28a745;
}

input:out-of-range {
  border-color: #dc3545;
}

Read Only and Read Write

input:read-only {
  background-color: #f8f9fa;
}

input:read-write {
  background-color: white;
}

Placeholder Shown

input:placeholder-shown {
  border-color: #dee2e6;
}

input:not(:placeholder-shown) {
  border-color: #007bff;
}

Negation Pseudo-Class

/* All paragraphs except first */
p:not(:first-child) {
  margin-top: 1em;
}

/* All inputs except checkboxes */
input:not([type="checkbox"]) {
  padding: 8px;
}

/* Multiple negations */
a:not(.active):not(.disabled) {
  color: #007bff;
}

Target Pseudo-Class

/* Highlighted section from URL hash */
section:target {
  background-color: #fff3cd;
  border-left: 4px solid #ffc107;
}

Empty Pseudo-Class

.message:empty {
  display: none;
}

div:empty::before {
  content: "No content available";
  color: #6c757d;
}

Root Pseudo-Class

:root {
  --primary-color: #007bff;
  --secondary-color: #6c757d;
  font-size: 16px;
}

Language Pseudo-Class

:lang(en) {
  quotes: '"' '"';
}

:lang(fr) {
  quotes: '« ' ' »';
}

Practical Examples

Striped Table

tr:nth-child(even) {
  background-color: #f8f9fa;
}

tr:hover {
  background-color: #e9ecef;
}

Form Validation Styles

input:valid {
  border-color: #28a745;
  background-image: url('check.svg');
  background-repeat: no-repeat;
  background-position: right 10px center;
}

input:invalid:not(:focus) {
  border-color: #dc3545;
}

input:focus {
  outline: none;
  border-color: #007bff;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.3);
}

.nav-link:hover {
  color: #007bff;
}

.nav-link.active,
.nav-link:target {
  color: #007bff;
  border-bottom: 2px solid #007bff;
}

Card Hover Effect

.card {
  transition: all 0.3s ease;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.15);
}

.card:hover .card-title {
  color: #007bff;
}

Accordion

.accordion-item:target .accordion-content {
  max-height: 500px;
}

.accordion-item:not(:target) .accordion-content {
  max-height: 0;
  overflow: hidden;
}

Disabled Button

button:disabled {
  background-color: #6c757d;
  cursor: not-allowed;
  opacity: 0.6;
}

button:not(:disabled):hover {
  background-color: #0056b3;
}

Combining Pseudo-Classes

/* Hover on enabled buttons only */
button:enabled:hover {
  background-color: #0056b3;
}

/* First child that's also hovered */
li:first-child:hover {
  font-weight: bold;
}

/* Valid input that has focus */
input:valid:focus {
  border-color: #28a745;
}

Best Practices

Pseudo-Class Best Practices

Use :hover and :focus together for accessibility
Prefer :focus-visible over :focus for keyboard users
Use :not() to avoid repetitive overrides
Style :disabled to show unavailable actions
Use :valid and :invalid for form feedback
Remember LVHA order for links (Link, Visited, Hover, Active)
Test pseudo-classes with keyboard navigation
Use :nth-child() for patterns and stripes
Combine pseudo-classes for specific selections
Consider touch devices (no hover)

Accessibility

/* Ensure focus is visible */
a:focus-visible,
button:focus-visible {
  outline: 3px solid #007bff;
  outline-offset: 2px;
}

/* Don't remove focus without alternative */
*:focus:not(:focus-visible) {
  outline: none;
}

/* Indicate disabled state clearly */
button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

Browser Support

Most pseudo-classes have excellent browser support. :focus-visible requires modern browsers. Always test in target browsers.

Master pseudo-classes to create dynamic, interactive, accessible interfaces!

Pseudo-classes select elements based on their state or position. They're essential for creating interactive, dynamic interfaces.

Common Pseudo-Classes

Link States

a:link {
  color: #007bff; /* Unvisited */
}

a:visited {
  color: #6610f2; /* Visited */
}

a:hover {
  color: #0056b3; /* Mouse over */
}

a:active {
  color: #ff3300; /* Being clicked */
}

Focus

input:focus {
  outline: 2px solid #007bff;
  border-color: #007bff;
}

button:focus-visible {
  outline: 3px solid #007bff;
  outline-offset: 2px;
}

.element:focus-within {
  /* When any child has focus */
  border-color: #007bff;
}

Structural Pseudo-Classes

First and Last

li:first-child {
  font-weight: bold;
}

li:last-child {
  border-bottom: none;
}

p:first-of-type {
  font-size: 1.2em;
}

p:last-of-type {
  margin-bottom: 0;
}

Nth Child

/* Even rows */
tr:nth-child(even) {
  background-color: #f8f9fa;
}

/* Odd rows */
tr:nth-child(odd) {
  background-color: white;
}

/* Every third item */
li:nth-child(3n) {
  color: #007bff;
}

/* First 3 items */
li:nth-child(-n+3) {
  font-weight: bold;
}

/* All but first 3 */
li:nth-child(n+4) {
  opacity: 0.7;
}

Nth of Type

p:nth-of-type(2) {
  color: #007bff;
}

div:nth-of-type(odd) {
  background-color: #f8f9fa;
}

Only Child

li:only-child {
  list-style: none;
}

p:only-of-type {
  text-align: center;
}

User Action Pseudo-Classes

Hover

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

button:hover {
  background-color: #0056b3;
}

Active

button:active {
  transform: scale(0.95);
}

.link:active {
  color: #ff3300;
}

Focus

input:focus {
  border-color: #007bff;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.3);
}

Input Pseudo-Classes

Enabled and Disabled

input:enabled {
  background-color: white;
}

input:disabled {
  background-color: #e9ecef;
  cursor: not-allowed;
  opacity: 0.6;
}

Checked

input[type="checkbox"]:checked {
  background-color: #007bff;
}

input[type="radio"]:checked + label {
  font-weight: bold;
  color: #007bff;
}

Valid and Invalid

input:valid {
  border-color: #28a745;
}

input:invalid {
  border-color: #dc3545;
}

input:required {
  border-left: 3px solid #007bff;
}

input:optional {
  border-left: 3px solid #6c757d;
}

In Range and Out of Range

input:in-range {
  border-color: #28a745;
}

input:out-of-range {
  border-color: #dc3545;
}

Read Only and Read Write

input:read-only {
  background-color: #f8f9fa;
}

input:read-write {
  background-color: white;
}

Placeholder Shown

input:placeholder-shown {
  border-color: #dee2e6;
}

input:not(:placeholder-shown) {
  border-color: #007bff;
}

Negation Pseudo-Class

/* All paragraphs except first */
p:not(:first-child) {
  margin-top: 1em;
}

/* All inputs except checkboxes */
input:not([type="checkbox"]) {
  padding: 8px;
}

/* Multiple negations */
a:not(.active):not(.disabled) {
  color: #007bff;
}

Target Pseudo-Class

/* Highlighted section from URL hash */
section:target {
  background-color: #fff3cd;
  border-left: 4px solid #ffc107;
}

Empty Pseudo-Class

.message:empty {
  display: none;
}

div:empty::before {
  content: "No content available";
  color: #6c757d;
}

Root Pseudo-Class

:root {
  --primary-color: #007bff;
  --secondary-color: #6c757d;
  font-size: 16px;
}

Language Pseudo-Class

:lang(en) {
  quotes: '"' '"';
}

:lang(fr) {
  quotes: '« ' ' »';
}

Practical Examples

Striped Table

tr:nth-child(even) {
  background-color: #f8f9fa;
}

tr:hover {
  background-color: #e9ecef;
}

Form Validation Styles

input:valid {
  border-color: #28a745;
  background-image: url('check.svg');
  background-repeat: no-repeat;
  background-position: right 10px center;
}

input:invalid:not(:focus) {
  border-color: #dc3545;
}

input:focus {
  outline: none;
  border-color: #007bff;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.3);
}

.nav-link:hover {
  color: #007bff;
}

.nav-link.active,
.nav-link:target {
  color: #007bff;
  border-bottom: 2px solid #007bff;
}

Card Hover Effect

.card {
  transition: all 0.3s ease;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.15);
}

.card:hover .card-title {
  color: #007bff;
}

Accordion

.accordion-item:target .accordion-content {
  max-height: 500px;
}

.accordion-item:not(:target) .accordion-content {
  max-height: 0;
  overflow: hidden;
}

Disabled Button

button:disabled {
  background-color: #6c757d;
  cursor: not-allowed;
  opacity: 0.6;
}

button:not(:disabled):hover {
  background-color: #0056b3;
}

Combining Pseudo-Classes

/* Hover on enabled buttons only */
button:enabled:hover {
  background-color: #0056b3;
}

/* First child that's also hovered */
li:first-child:hover {
  font-weight: bold;
}

/* Valid input that has focus */
input:valid:focus {
  border-color: #28a745;
}

Best Practices

Pseudo-Class Best Practices

Use :hover and :focus together for accessibility
Prefer :focus-visible over :focus for keyboard users
Use :not() to avoid repetitive overrides
Style :disabled to show unavailable actions
Use :valid and :invalid for form feedback
Remember LVHA order for links (Link, Visited, Hover, Active)
Test pseudo-classes with keyboard navigation
Use :nth-child() for patterns and stripes
Combine pseudo-classes for specific selections
Consider touch devices (no hover)

Accessibility

/* Ensure focus is visible */
a:focus-visible,
button:focus-visible {
  outline: 3px solid #007bff;
  outline-offset: 2px;
}

/* Don't remove focus without alternative */
*:focus:not(:focus-visible) {
  outline: none;
}

/* Indicate disabled state clearly */
button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

Browser Support

Most pseudo-classes have excellent browser support. :focus-visible requires modern browsers. Always test in target browsers.

Master pseudo-classes to create dynamic, interactive, accessible interfaces!

CSS Pseudo-Classes

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CSS Pseudo-Classes

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