CSS Flexbox Playground — Free Tool

What Is Flexbox?

CSS Flexbox is a layout model designed for distributing space and aligning items within a container — even when their sizes are unknown or dynamic. Before Flexbox, centering elements and creating equal-height columns required hacks with floats, tables, or absolute positioning. Flexbox solved all of that with a clean, intuitive property system.

This playground lets you experiment with every Flexbox property in real time: flex-direction, justify-content, align-items, flex-wrap, gap, and individual item properties like flex-grow, flex-shrink, and align-self. See exactly how each property affects your layout without writing a line of code.

Key Flexbox Properties

flex-direction controls the main axis (row or column). justify-content distributes items along the main axis (start, center, space-between, space-around, space-evenly). align-items aligns items on the cross axis (stretch, center, start, end, baseline). flex-wrap determines whether items wrap to new lines or stay in one row.

Tips for Using Flexbox

→ Use gap instead of margins. The gap property adds consistent spacing between flex items without affecting the outer edges — cleaner than margin hacks.
→ flex: 1 makes items fill space equally. Apply flex: 1 to all children to distribute available space evenly, regardless of content size.
→ Use min-width: 0 to prevent overflow. Flex items won't shrink below their content size by default. Adding min-width: 0 allows them to shrink properly.
→ Combine with Grid. Use Flexbox for component-level layouts (navbars, cards, buttons) and CSS Grid for page-level layouts.

How to Use This Flexbox Playground

Set the flex container properties — Configure flex-direction, justify-content, align-items, flex-wrap, and gap on the parent container.
Add and remove flex items — Add child elements and see how they distribute within the container based on your settings.
Adjust individual item properties — Set flex-grow, flex-shrink, flex-basis, and align-self on individual items to control their sizing behavior.
Experiment with layouts — Try common patterns — centered content, sidebar+main, equal columns, holy grail layout — using different property combinations.
Copy the CSS — Grab the complete flexbox CSS for both the container and items.

Tips and Best Practices

→ Use gap instead of margins. The gap property on flex containers creates consistent spacing without margin hacks. It's cleaner and doesn't add spacing on the outer edges.
→ flex: 1 makes items grow equally. Setting flex: 1 on all children makes them share available space equally — the most common pattern for multi-column layouts.
→ Use flex-wrap for responsive grids. Combine flex-wrap: wrap with flex-basis to create responsive card grids that wrap naturally without media queries.
→ Flexbox is one-dimensional. Flexbox handles layout in one direction at a time (row or column). For two-dimensional layouts (rows AND columns simultaneously), use CSS Grid. See our CSS Grid Generator.

Frequently Asked Questions

What is CSS Flexbox?

CSS Flexbox (Flexible Box Layout) is a one-dimensional layout model that distributes space among items in a container along a single axis. It simplifies centering, spacing, alignment, and responsive reordering without floats or positioning hacks.

When should I use Flexbox vs Grid?

Use Flexbox for one-dimensional layouts — a single row or column of items. Use CSS Grid for two-dimensional layouts where you need control over both rows and columns simultaneously. Many modern layouts combine both.

How do I center a div with Flexbox?

Apply display: flex; justify-content: center; align-items: center; to the parent container. This centers the child both horizontally and vertically — the most common and simplest Flexbox pattern.

What is CSS Flexbox?+

Flexbox (Flexible Box Layout) is a CSS layout model that distributes space and aligns items within a container — either horizontally (row) or vertically (column). It simplifies common layout patterns like centering, equal-height columns, sticky footers, and responsive navigation that were difficult or hacky with floats and positioning.

When should I use Flexbox vs CSS Grid?+

Use Flexbox for one-dimensional layouts — a row of buttons, a navigation bar, centering a single element, or distributing items along one axis. Use CSS Grid for two-dimensional layouts — page layouts with rows AND columns, card grids, and complex dashboards. They can be combined: Grid for the page layout, Flexbox for components within grid cells.

What does flex: 1 1 0 mean?+

It's shorthand for flex-grow: 1 (take available space), flex-shrink: 1 (shrink if needed), flex-basis: 0 (start from zero width/height). This makes the item grow to fill its share of the container's available space equally with other flex: 1 siblings. It's the most common flex shorthand.

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Built by Derek Giordano · Part of Ultimate Design Tools

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