How to Generate CSS Flexbox Layouts

Flexbox is the foundation of modern CSS layouts, but remembering which combination of justify-content, align-items, and flex-wrap produces the layout you want can be frustrating. The CSS Flexbox Generator lets you configure layouts visually and generates the exact CSS you need, eliminating the trial-and-error cycle.

Understanding flexbox layout

Flexbox works along two axes: the main axis (defined by flex-direction) and the cross axis (perpendicular to it). All flexbox behavior stems from how items are distributed along these two axes.

The container properties control the overall layout: flex-direction sets the main axis (row or column), justify-content distributes items along the main axis, align-items aligns items along the cross axis, flex-wrap controls whether items wrap to new lines, and gap sets spacing between items.

Item properties control individual behavior within the container: flex-grow determines how extra space is distributed (a value of 1 means the item grows to fill available space), flex-shrink controls how items shrink when space is tight, and flex-basis sets the initial size before growing or shrinking is applied.

The shorthand flex: 1 1 0% (grow, shrink, basis) is the most common pattern for equal-width items. For a fixed-width item that does not flex, use flex: 0 0 auto with an explicit width.

Tips and best practices

• Use gap instead of margins. The gap property on the flex container is cleaner than adding margins to items. It only adds space between items, not around the outside edges.
• Start with flex-wrap: wrap for responsive layouts. Without wrapping, flex items will shrink indefinitely to fit on one line, often squishing content. Wrapping lets items flow to new lines when space runs out.
• Use min-width: 0 on flex items to prevent overflow. By default, flex items will not shrink below their content size. If long text or large images overflow, adding min-width: 0 allows the item to shrink properly.
• Combine flex-grow with flex-basis for proportional layouts. Instead of using percentages, set flex-basis: 0 and use different flex-grow values to create proportional columns (e.g., flex: 2 and flex: 1 for a 2:1 ratio).

Common issues

• Items not centering vertically. Make sure the flex container has an explicit height. If the container’s height matches its content height, there is no extra space for align-items: center to work with.
• Last row of wrapped items stretching unexpectedly. When using justify-content: space-between with wrapping, the last row may spread items across the full width if it has fewer items. Use gap with flex-basis percentages instead for grid-like wrapped layouts.
• Flex items ignoring width. When flex-basis is set, it overrides width in the main axis direction. Use flex-basis instead of width for sizing flex items, or set flex-basis: auto to respect the width property.