DevBolt
Processed in your browser. Your data never leaves your device.

How do I build a CSS flexbox layout online?

Set flex container properties (direction, wrap, justify-content, align-items, gap) and configure individual flex items using visual controls. See a live preview of your layout and copy the production-ready CSS. Choose from presets like navbar, card grid, or holy grail. Everything runs in your browser.

Center content horizontally & vertically
Input
Direction: row
Justify: center
Align: center
Gap: 16px
Output
.container {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
}
← Back to tools

CSS Flexbox Generator

Build CSS flexbox layouts visually. Configure container and item properties, preview live, and copy the CSS.

Container Properties

px

Live Preview

Click an item to configure its flex properties

CSS Output

.container {
  display: flex;
  flex-direction: row;
  justify-content: flex-start;
  align-items: stretch;
  flex-wrap: nowrap;
  gap: 12px;
}

Layout Presets

About CSS Flexbox

Flexbox is a one-dimensional layout model that distributes space among items in a container and controls their alignment.

flex-direction sets the main axis. row is horizontal (default), column is vertical.

justify-content aligns items along the main axis. align-items aligns items along the cross axis.

flex-grow controls how much an item grows relative to siblings. flex-shrink controls how much it shrinks. flex-basis sets the initial size before growing or shrinking.

flex-wrap allows items to flow onto multiple lines when they exceed the container width. align-content controls spacing between wrapped lines.

gap adds consistent spacing between flex items without needing margins.

Tips & Best Practices

Pro Tip

Use gap instead of margin for consistent spacing

The gap property (gap: 16px) creates uniform spacing between flex items without affecting the first/last item. Before gap support, developers used margin with negative margin on the container or :last-child overrides. gap works in Flexbox (all modern browsers since 2021) and eliminates spacing hacks.

Common Pitfall

flex: 1 doesn't mean equal widths — it means equal growth

flex: 1 sets flex-grow: 1, flex-shrink: 1, flex-basis: 0%. Items grow equally from 0 width, but content can make them unequal. For truly equal widths, use flex: 1 1 0% AND min-width: 0 (to allow items to shrink below content size). Or use CSS Grid with grid-template-columns: repeat(3, 1fr).

Real-World Example

Centering anything: display:flex + place-items:center

The CSS holy grail — centering vertically and horizontally — is one line: display: flex; place-items: center (shorthand for align-items + justify-items). Or use place-content: center for the container-level equivalent. No more margin: auto, transform: translate(-50%), or table-cell hacks.

Security Note

Flexbox order changes visual order, not DOM order

The CSS order property rearranges visual display but screen readers and keyboard navigation follow DOM order. If your flex order creates a different visual sequence than the tab order, keyboard users will be confused and disoriented. Keep visual and DOM order aligned for accessible navigation.

Frequently Asked Questions

How do I center an element vertically and horizontally with Flexbox?
Apply display: flex to the parent container, then set justify-content: center and align-items: center. This centers child elements both horizontally and vertically. If you need full-viewport centering, add height: 100vh to the parent. This is the most reliable centering technique in modern CSS, replacing older hacks involving position absolute with transforms or table-cell display. DevBolt's Flexbox Generator lets you toggle these properties visually and see the layout update in real time, then copy the generated CSS directly.
What is the difference between flex-wrap and flex-shrink?
flex-wrap controls whether flex items are forced onto a single line or allowed to wrap onto multiple lines. The default nowrap keeps all items on one line. Setting flex-wrap: wrap allows items to flow to the next row when they exceed container width. flex-shrink controls how much an individual item shrinks relative to others when the container is too small. The default value of 1 means items shrink equally. Setting flex-shrink: 0 prevents an item from shrinking. Use flex-wrap for responsive layouts and flex-shrink to control which items compress first.
When should I use Flexbox instead of CSS Grid?
Use Flexbox for one-dimensional layouts where content flows in a single row or column. Flexbox excels at navigation bars, button groups, card rows, and form input layouts. Use CSS Grid when you need two-dimensional control over both rows and columns simultaneously, such as full-page layouts, dashboards, or image galleries. A practical rule: if your layout is a line of items, use Flexbox. If it is a grid of cells, use Grid. Many real-world layouts combine both. DevBolt offers visual builders for both approaches.

Related Generate Tools

◜◝

Border Radius Generator

Design CSS border-radius visually with per-corner controls, unit selection, and presets

Tˢ

Text Shadow Generator

Design CSS text shadows visually with multiple layers, presets, and live preview

ANI

CSS Animation Generator

Build CSS keyframe animations visually with presets, live preview, and copy-ready code

TBL

Markdown Table Generator

Build Markdown tables visually with an interactive editor, CSV import, and alignment controls