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css-flexbox-generator

A CSS flexbox generator is a visual tool that lets you compose display: flex containers by toggling each flex property and seeing the result in real time. The ZTools CSS Flexbox Generator covers every flex container property (flex-direction, justify-content, align-items, align-content, flex-wrap, gap) and per-child properties (flex-grow, flex-shrink, flex-basis, align-self), generating both the parent and child CSS in copy-paste-ready form. Designed for developers who know flexbox conceptually but find the property combinations hard to memorize.

Use cases​

Set justify-content: space-between plus a flex spacer trick, see the result, copy the CSS. Faster than tweaking margin values until it looks right.

Centering content vertically AND horizontally​

The classic "how do I center a div" — set justify-content: center + align-items: center on the parent. The generator shows you exactly that combination with a live preview.

Building responsive card grids that wrap gracefully​

Set flex-wrap: wrap + gap: 1rem, watch cards reflow as the preview width changes. Copy the CSS and apply to your real grid.

Learning flexbox without trial-and-error​

Each property has a tooltip explaining its behavior. Toggle and see — the preview makes flexbox's otherwise-confusing rules immediately visible.

How it works​

  1. Choose the number of children — Slider from 1 to 12 children. Each child renders as a colored block in the preview.
  2. Set parent (container) properties — Toggle flex-direction, flex-wrap, justify-content, align-items, align-content, gap. Each click updates the preview instantly.
  3. Optionally set per-child properties — Click any child block to set its flex-grow, flex-shrink, flex-basis, or align-self independently.
  4. Preview at multiple widths — Drag the preview width slider to test how the layout reflows on narrow vs wide screens.
  5. Copy generated CSS — Output includes a .container \{ display: flex; ... \} block plus per-child overrides if you set any. One click copies the full snippet.

Examples​

Input: flex-direction: row, justify-content: space-between, align-items: center

Output: .container { display: flex; flex-direction: row; justify-content: space-between; align-items: center; }

Input: flex-direction: column, gap: 1rem, align-items: stretch

Output: .container { display: flex; flex-direction: column; gap: 1rem; align-items: stretch; }

Frequently asked questions​

When should I use flexbox vs grid?

Flexbox for one-dimensional layouts (a row OR a column). Grid for two-dimensional layouts (rows AND columns simultaneously). Both can be combined in the same page.

Why doesn't justify-content: center center my content vertically?

Because justify-content works on the main axis (horizontal in a row layout). For vertical centering in a row, use align-items: center. The generator labels each property by axis to avoid this confusion.

What does flex: 1 mean?

Shorthand for flex: 1 1 0% — grow to fill available space, shrink if needed, and start from 0 width. Common for equal-width children: <div style="flex: 1"> × N gives N equal columns.

How do I make children wrap to a new line?

Set flex-wrap: wrap on the container. Without it, children shrink to fit on one line (or overflow). The generator includes wrap toggling so you can see the effect immediately.

What's the difference between gap and margin?

gap applies space between children only — no leading/trailing space at the container edges. margin on children produces both interior and edge space, often requiring :last-child overrides. Prefer gap in modern CSS.

Is the generated CSS production-ready?

Yes — uses standard, evergreen-browser-supported properties. No vendor prefixes needed since 2018.

Tips​

  • Default to gap for spacing between flex children — no more :not(:last-child) \{ margin-right \} hacks.
  • For equal-width columns, use flex: 1 on every child instead of fixed widths.
  • Combine flexbox with min-width: 0 on children when text might overflow — fixes the "ellipsis not working" gotcha.
  • Use the generator to learn flexbox visually, then graduate to writing CSS by hand.

Try it now​

The full css-flexbox-generator runs in your browser at https://ztools.zaions.com/css-flexbox-generator — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-05 · Author: Ahsan Mahmood · Edit this page on GitHub