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CSS

CSS Overview Selectors Declarations Rule Sets Comments Reset/Normalize Origin Importance Order Specificity Inheritance Cascade Layers Inline Styles Internal Styles External Styles @import Absolute Units Relative Units Dynamic Viewport Angle Units Time Units Frequency Units: Resolution Units Keywords Color Formats Color Functions & Spaces Background Color Background Image Background Repeat Background Position Background Size Background Attachment Background Shorthand Multiple Backgrounds Linear Gradients Radial Gradients Conic Gradients Font Family Font Size Font Weight Font Style Line Height Text Align Text Decoration Text Transform Letter Spacing Word Spacing Text Shadow Text Wrap Variable Fonts Content Box Padding Box Border Box Margin Box Box Sizing Property Margin Padding Border Outline Box Shadow Block Display Inline Display Inline Block Display Static Position Relative Position Absolute Position Fixed Position Sticky Position Top Element Position Right Element Position Bottom Element Position Left Element Position Z Index Flexbox Box Layout Display Flex Flex Direction Flex Wrap Justify Content Align Items Align Content Gap, Row Gap & Column Gap Flex Grow Flex Shrink Flex Basis Flex Shorthand Order Property Align Self Practical Applications CSS Grid Layout Grid Display Grid Template Columns Grid Template Rows Grid Template Areas Justify Items Grid Auto Columns Justify Self Nested Grids Responsive Web Design Min Width Max Width Orientation Logical Operators Pointer Hover Prefers Color Scheme Fluid Images Flexible Typography Viewport Width Advanced CSS Features Defining variables Using variables Scope & Inheritance of CSS Variables Property Value Fallback Practical Applications :Hover :Active :Focus :Focus Visible :Visited :Link :First Child :Last Child :Nth Child :Nth of Type :Empty :Checked :Disabled :Enabled :Valid :Invalid :Required :Has :Not :Is :Where ::Before Pseudo Element ::After Pseudo Element ::First Letter ::First Line ::Selection ::Marker CSS 2D Transformations CSS 3D Transformations Transform Origin Transform Style Backface Visibility Transition Property Transition Duration Transition Timing Function Transition Delay Transition Shorthand Ease Timing Function Linear Timing Function Ease In Timing Function Ease Out Timing Function Ease In Out Timing Function Cubic Bezier Function Animations (@keyframes) Defining @keyframes Animation Name CSS Animation Duration Animation Timing Function CSS Animation Delay CSS Animation Iteration Count Animations Direction CSS Animation Fill Mode CSS Animation Play State CSS Filter Blur CSS Filter Brightness CSS Filter Contrast() CSS Drop Shadow CSS Grayscale CSS Hue Rotate CSS Invert CSS Opacity CSS Saturate CSS Sepia Mix Blend Mode Background Blend Mode Object Fit & Object Position Scroll Snap Type Scroll Snap Align Scroll Padding Scroll Margin Scroll Triggered Animations JS Variables

:Focus

The :focus pseudo-class applies styles to an element that has received focus, either through a mouse click or by tabbing with the keyboard. It is commonly used on form elements like <input>, <textarea>, and <select>.

Example 1: Input Focus

/* Style for an input field */
.my-input {
  border: 1px solid #ced4da;
  padding: 8px;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

/* Add a colored border and shadow when the input is focused */
.my-input:focus {
  outline: none;
  border-color: #007bff;
  box-shadow: 0 0 5px rgba(0, 123, 255, 0.5);
}

Explanation

When a user clicks on or tabs to the input field, the default outline is removed, and a blue border with a subtle glow is added, improving the visual cue for the focused element.

Example 2: Textarea Focus

/* Style for a textarea */
.my-textarea {
  border: 1px solid #ced4da;
  padding: 8px;
  transition: background-color 0.3s ease;
}

/* Change the background color of the textarea when it is focused */
.my-textarea:focus {
  background-color: #f8f9fa;
}

Explanation

This code changes the background color of the textarea when it receives focus, making it clear to the user which field they are currently editing.

Example 3: Link Focus

/* Style for a link */
.my-link {
  color: #007bff;
  text-decoration: none;
  padding: 5px;
  border-radius: 3px;
}

/* Add a background color to the link when it is focused */
.my-link:focus {
  background-color: #e9ecef;
  outline: 2px solid #007bff;
}

Explanation

For accessibility, it's important to style the focus state of links. This example adds a background color and a distinct outline when a link is focused via the keyboard.

Example 4: Div with tabindex Focus

/* Style for a focusable div */
.focusable-div {
  padding: 20px;
  border: 2px dashed #6c757d;
}

/* Change the border style and color when the div is focused */
.focusable-div:focus {
  outline: none;
  border-style: solid;
  border-color: #6c757d;
}

Explanation

By adding a tabindex="0" attribute to the div in the HTML, it becomes focusable. This CSS then changes the border from dashed to solid when the user tabs to the div.

Example 5: Animated Border on Focus

/* Style for an input field */
.animated-input {
  border: 2px solid transparent;
  background-image: linear-gradient(white, white),
    linear-gradient(to right, #007bff, #28a745);
  background-origin: border-box;
  background-clip: padding-box, border-box;
}

/* Animate the border on focus */
.animated-input:focus {
  animation: rotate-border 1.5s linear infinite;
}

@keyframes rotate-border {
  to {
    transform: rotate(360deg);
  }
}

Explanation

This advanced example uses a background gradient to create a colored border. When the input is focused, a CSS animation rotates the gradient, creating a visually engaging effect.