UCSSR

Flexbox Generator

Create and customize flexbox layouts with an intuitive visual editor.

Item 1
Item 2
Item 3
display: flex;
flex-direction: row;
justify-content: flex-start;
align-items: stretch;
flex-wrap: nowrap;
gap: 1rem;

Flexbox Guide

Flexbox is a powerful CSS layout model that revolutionizes how we design user interfaces. Unlike traditional layout methods, Flexbox provides a more efficient way to distribute space and align content within a container, even when dealing with dynamic or unknown sizes.

Key Concepts

Flex Container

The parent element that holds flex items. Created by setting display: flex or display: inline-flex. This container establishes a new flex formatting context for its children.

Flex Items

The direct children of a flex container. These items can be sized, ordered, and aligned according to the flex properties set on both the container and the items themselves.

The Two Axes

Main Axis

Defined by flex-direction:

  • row: left to right (default)
  • row-reverse: right to left
  • column: top to bottom
  • column-reverse: bottom to top

Cross Axis

Always perpendicular to the main axis:

  • For row/row-reverse: top to bottom
  • For column/column-reverse: left to right

Interactive Examples

The following examples demonstrate common flexbox patterns and their practical applications. Each example includes a live preview and the corresponding CSS code.

Basic Row Layout

The most common use of flexbox is to create horizontal layouts. Items are placed in a row and can be spaced and aligned easily.

1
2
3
display: flex;
gap: 1rem;
/* Items will flow from left to right */

Advanced Concepts

Flex Grow, Shrink, and Basis

These properties control how flex items grow and shrink within their container:

flex-grow

Determines how much an item can grow relative to other items when extra space is available. Default: 0 (won't grow)

flex-shrink

Controls how much an item can shrink relative to others when space is limited. Default: 1 (will shrink)

flex-basis

Sets the initial main size of an item before growing or shrinking. Default: auto

Order and Alignment

Flexbox provides powerful tools for controlling item order and alignment:

order Property

Changes the visual order of flex items without modifying the HTML structure.

  • Default value: 0
  • Lower values appear first
  • Same values maintain source order

align-self

Overrides the container's align-items for individual items.

  • Can target specific items
  • Useful for exceptions to general alignment
  • Same values as align-items

Common Use Cases

Holy Grail Layout

Header
Sidebar
Main Content
Aside
Footer

A classic web layout pattern with header, footer, and three columns. Flexbox makes this traditionally complex layout simple to implement and maintain.

Responsive Patterns

Flexbox excels at creating responsive layouts that adapt to different screen sizes:

Mobile-First Navigation

Use flex-direction: column on mobile and row on desktop. Combined with media queries, this creates seamless responsive navigation.

Card Layouts

Combine flex-wrap with percentage or fixed widths to create responsive card grids that automatically adjust to the container width.

Best Practices & Common Pitfalls

Performance Considerations

While flexbox is powerful, it's important to use it efficiently:

  • Avoid deeply nested flex containers when possible
  • Use CSS Grid for two-dimensional layouts
  • Consider using contain: strict for large lists of flex items
  • Be cautious with flex-grow on text containers

Debugging Tips

Common issues and how to solve them:

Items Not Wrapping

Check if:

  • flex-wrap is set correctly
  • items have appropriate min-width
  • container has sufficient width

Unexpected Item Sizes

Verify:

  • flex-basis settings
  • min/max-width constraints
  • flex-grow/shrink values

Useful Resources

CSS-Tricks Flexbox Guide

Complete visual guide to CSS flexbox

Flexbox Froggy

Learn flexbox through a fun game

MDN Flexbox Documentation

Comprehensive flexbox documentation

Flexbox Properties Quick Reference

↔️

flex-direction

Defines the main axis direction

row, column, row-reverse, column-reverse

⇔

justify-content

Aligns items along the main axis

flex-start, center, flex-end, space-between, space-around

⇕

align-items

Aligns items along the cross axis

flex-start, center, flex-end, stretch, baseline

↩️

flex-wrap

Controls item wrapping

nowrap, wrap, wrap-reverse

↔️

gap

Space between flex items

Any length or percentage

📦

display

Defines the flex container

flex, inline-flex

Browser Support