CSS Flexbox Playground

The CSS Flexbox Playground is a free online tool that visually experiment with flexbox container and item properties. generate css, tailwind, and html output with live preview and presets for common layouts.. It runs entirely in your browser with no installation or sign-up needed.

display:flex is a block-level flex container taking full parent width. inline-flex is inline-level and only takes its content width, flowing with surrounding text.

flex-basis sets initial size before free space is distributed. flex-grow defines how leftover free space is shared among items.

Parent: display:flex + justify-content:center + align-items:center. The Centered preset applies this exact configuration.

Yes, the CSS Flexbox Playground is 100% free with no registration, no hidden fees, and no usage limits. All processing happens locally in your browser, ensuring complete privacy.

Absolutely. The CSS Flexbox Playground processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the CSS Flexbox Playground is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the CSS Flexbox Playground in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

The CSS Flexbox Playground supports a wide range of popular formats and languages. Check the tool interface for the full list of supported options.

The CSS Flexbox Playground works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

These two properties move items along opposite axes. justify-content positions items along the main axis — the direction set by flex-direction, so it controls horizontal spacing in a row and vertical spacing in a column. align-items positions items along the cross axis, the perpendicular direction, so it handles vertical alignment in a row and horizontal in a column. That is why switching flex-direction from row to column appears to swap what each property does. justify-content offers values like flex-start, center, space-between, space-around, and space-evenly, while align-items offers stretch, flex-start, flex-end, center, and baseline. A simple way to remember it: justify spreads items across the line, align positions them up and down within it. In this playground you can toggle each property independently and watch the dashed preview rearrange instantly, which makes the main-axis versus cross-axis distinction obvious without memorizing it from the spec, then copy the resulting CSS or Tailwind classes.

Set the container to display:flex with flex-wrap:wrap so items move to a new line when they run out of room, then give each card a shared flex-basis to control how wide it is before wrapping. A basis like 200px combined with flex-grow lets cards expand to fill the row and reflow to fewer columns on narrow screens, all without media queries. Adding a gap keeps consistent spacing between rows and columns. The Card Grid preset in this playground loads exactly this setup — six wrapping cards sharing a flex-basis with a 16px gap — so you can study a working responsive layout, adjust the basis or item count, and watch columns reflow live as the preview width changes. Because the cards size themselves from their basis rather than a fixed column count, the same rules adapt from wide desktops down to phones. When it looks right, copy the generated CSS or Tailwind classes straight into your project.

flex is shorthand for three properties in order: flex-grow, flex-shrink, and flex-basis. So flex: 0 0 240px means flex-grow:0 (the item will not stretch to fill extra space), flex-shrink:0 (it will not shrink below its size even when space is tight), and flex-basis:240px (its starting width is fixed at 240px). The result is a rigid, fixed-width element — perfect for a sidebar that should stay 240px wide while the main content area flexes around it. The Sidebar Layout preset here uses this exact value for its fixed column beside a flexible main area. By contrast, flex: 1 expands to flex-grow:1, flex-shrink:1, flex-basis:0, which makes an item greedily fill available space — the opposite behavior. Because the playground exposes flex-grow, flex-shrink, and flex-basis as separate per-item controls on each item card, you can dial in this shorthand piece by piece, see the effect in the live preview, and copy the clean CSS output.

align-items only changes anything when items are smaller than the container along the cross axis, because it positions them within that leftover space. Two common situations hide its effect. First, the default align-items value is stretch, which makes items expand to fill the cross axis — so they already span the full height in a row and there is no gap to align within. Second, if every item is the same size as the container or has no explicit height, switching between flex-start, center, and flex-end produces no visible movement. Give items a fixed width or height, or change align-items away from stretch, and the alignment becomes obvious. You can also override a single item with align-self if you only want one child positioned differently. In this playground you can set per-item width and height on each item card, then toggle align-items to see exactly when it takes effect before copying the code.

flex-wrap controls whether flex items are forced onto a single line or allowed to flow onto multiple lines. With nowrap, the default, all items stay on one line and shrink to fit, which can squash them or cause overflow when there is not enough room. With wrap, items that do not fit move down to a new line, preserving their preferred size and creating a multi-row layout — essential for responsive card grids and tag lists. There is also wrap-reverse, which wraps onto new lines stacked in the opposite direction. Note that align-content, which distributes those wrapped lines, only has an effect once wrapping actually produces more than one line. This playground exposes nowrap, wrap, and wrap-reverse as a single control, so you can flip between them and watch items reflow in the live preview before copying the code.