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Lizely

Flexbox Generator

Configure five core Flexbox controls, inspect a fixed multi-item preview, and copy deterministic CSS without arbitrary style input.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Choose the flex direction, wrapping mode, main-axis distribution, and cross-axis item alignment.
  2. 2.Enter a whole-pixel gap from 0 through 100 and inspect the five fixed preview items.
  3. 3.Generate the validated .container rule, then copy it or select the visible code manually.

About Flexbox Generator

Flexbox Generator builds a focused CSS declaration block for one flex container. Choose flex-direction, flex-wrap, justify-content, align-items, and a whole-pixel gap from 0 through 100. A five-item preview updates only when every field is valid. Generate CSS then creates a deterministic .container rule that can be selected or copied. Preview and copied declarations derive from the same validated settings, so the two representations cannot silently use different values. The tool never accepts arbitrary property names, selectors, URLs, fragments, or executable style text. The keyword lists are closed subsets drawn from the W3C Flexbox and Box Alignment specifications. Direction supports row, row-reverse, column, and column-reverse. Wrapping supports nowrap, wrap, and wrap-reverse. Main-axis distribution supports flex-start, flex-end, center, space-between, space-around, and space-evenly. Cross-axis item alignment supports stretch, flex-start, flex-end, center, and baseline. Every selected value is validated against its list again before it reaches either the preview style object or generated text. Flexbox has a main axis and a cross axis. flex-direction establishes the main axis and ordering, so justify-content operates horizontally for an ordinary row but vertically for a column. align-items works on the cross axis for items within each flex line. flex-wrap decides whether items remain on one line, form additional lines, or form lines in the reverse cross-axis direction. The preview uses five fixed local items so these interactions can be explored without importing markup or content. Item size, writing mode, container dimensions, and available space still influence real layouts. The gap field represents spacing between adjacent flex items and flex lines. This generator intentionally accepts only base-10 whole numbers with an implicit px unit. Zero and 100 are accepted. Negative values, decimals, scientific notation, unit text, empty input, CSS punctuation, leading zero forms such as 00, and values above 100 are rejected. Numbers above the supported range are reported rather than reduced to 100. Raw gap text is limited to 32 UTF-16 code units; exact-boundary input is processed and longer input fails without truncation. The preview receives an explicit px string made from the same validated numeric gap serialized into the output. Generated output always contains exactly six declarations: display:flex plus the five configured properties. Declaration names and order are fixed. The generator does not emit vendor prefixes, child flex shorthand, flex-basis, grow or shrink factors, order, align-content, place-content, dimensions, overflow, media queries, or fallbacks. It is a safe container starting point rather than a complete responsive layout system. Copying these declarations into a container with different content or dimensions may naturally produce different wrapping than the demonstration. Editing any select or the gap immediately removes prior generated CSS, a validation error, and copied confirmation. Generate validates the complete current state before restoring output. Invalid enum state and invalid gap state show the actual validation message; invalid text never reaches inline style or copied CSS. The Clipboard API is asynchronous. Each copy receives a generation identity, and every edit, generation, later copy, or component unmount invalidates older completion. A confirmation timer is cleared when superseded or unmounted and clears its own reference after firing. A failed copy leaves the complete CSS visible for manual selection. All validation, preview rendering, serialization, and clipboard work occur locally in the active browser tab. No setting or generated CSS is uploaded to Lizely. The tool creates no file, Blob URL, remote stylesheet, embedded frame, or dynamically executed CSS string. Use the result in your own reviewed stylesheet, add child rules and responsive constraints there, and test it with real content, writing modes, viewport sizes, zoom, and accessibility settings before shipping.

Methodology & sources

Store every supported CSS keyword in a closed immutable enumeration and validate all strings again before use. Parse gap with a strict base-10 whole-number grammar, accepting 0 through 100 inclusive and failing raw text beyond 32 code units without truncation or capping. Serialize one fixed .container block containing display:flex, flex-direction, flex-wrap, justify-content, align-items, and gap. Build the live preview from the exact same validated typed settings, with gap explicitly expressed in px. Editing clears prior output and errors. Clipboard jobs use generation and alive guards plus timer cleanup so stale asynchronous completion cannot restore copied state. Eight executable golden combinations cover every supported keyword, both gap boundaries, output order, preview parity, enum uniqueness, malformed values, and CSS-injection attempts.

Frequently asked questions

What is the difference between justify-content and align-items?
justify-content distributes items along the main axis established by flex-direction. align-items positions items along the cross axis within each flex line.
Why does changing flex-direction change the alignment direction?
A row makes the inline direction the main axis, while a column makes the block direction the main axis. justify-content follows that main axis.
Can I enter CSS units other than pixels?
No. This focused generator accepts only whole-pixel gaps from 0 through 100 and rejects unit text rather than inserting it into CSS.
Is the copied CSS uploaded or executed remotely?
No. Validation, preview, serialization, and clipboard copying happen locally in the current browser tab.

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