Flexbox Generator: Create CSS Flexbox Properties Visually
Build CSS Flexbox container and item properties visually with live preview, all flex properties supported, and copy-ready CSS output.
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CSS Flexbox transformed web layout by making it trivial to center elements, distribute space evenly, and create responsive row and column layouts without floats or positioning hacks. Despite its elegance, Flexbox has a learning curve: the interplay between container properties (flex-direction, justify-content, align-items, flex-wrap) and item properties (flex-grow, flex-shrink, flex-basis) can be confusing until you have built an intuitive mental model.
Our Flexbox Generator provides an interactive playground where you adjust every flex property through visual controls and see the result update in real time on a live preview with draggable items. You can add and remove items, resize the container, and experiment with every property combination without writing a single line of CSS. The generated code panel shows exactly which properties you have changed, keeping the output lean.
Whether you are learning Flexbox for the first time or debugging a tricky alignment issue in a production layout, this tool makes the feedback loop immediate and the relationship between properties and behavior clear.
What Is CSS Flexbox?
CSS Flexbox (Flexible Box Layout) is a one-dimensional layout model that distributes space among items in a container along a main axis and aligns them along a cross axis. The main axis is defined by flex-direction — either horizontal (row) or vertical (column). Flexbox makes it straightforward to align items, distribute available space, and handle overflow in ways that adapt to the container's size.
A flex container is created by setting display: flex or display: inline-flex on an element. All direct children of that element become flex items and participate in the flex layout. Flex items can be sized using the flex shorthand, which combines flex-grow (how much they expand), flex-shrink (how much they contract), and flex-basis (their starting size before growing or shrinking).
Flexbox is particularly well-suited for navigation bars, toolbars, card rows, form layouts, and any component where items should be arranged and aligned along a single axis with intelligent space distribution.
How to Use This Tool
Explore and configure Flexbox properties interactively:
- 1
Configure the Container
Use the container panel to set flex-direction, flex-wrap, justify-content, align-items, and align-content. Each property has a visual button group showing what each value does with a small icon, so you do not need to memorize the syntax.
- 2
Add and Configure Items
Click 'Add Item' to add flex items to the preview. Select any item and use the item panel to set flex-grow, flex-shrink, flex-basis, align-self, and order for that specific item.
- 3
Resize the Container
Drag the resize handle on the preview container to change its width. Watch how items redistribute as the available space grows and shrinks — this is the core of understanding flex-grow and flex-shrink.
- 4
Experiment with gap
Set column-gap and row-gap values using the gap controls. Gap in Flexbox creates consistent spacing between items without affecting the outer edges of the container.
- 5
Copy the CSS
The CSS output panel updates live. Copy just the container properties, just the item properties, or the complete set. Items with their default flex values (0 1 auto) are omitted to keep the output clean.
Common Use Cases
Flexbox solves a wide range of everyday layout challenges:
- Centering an element both horizontally and vertically inside a container using justify-content: center and align-items: center on the flex parent
- Building navigation bars where a logo is on the left, navigation links are in the middle, and action buttons are on the right using justify-content: space-between
- Creating responsive card rows where cards wrap to a new row when the container is too narrow, using flex-wrap: wrap with a fixed flex-basis on each card
- Building form layouts where labels and inputs are aligned in a row or stacked in a column depending on available space
- Making footer content stick to the bottom of a variable-height page layout using a flex column on the body with flex-grow: 1 on the main content area
Tips and Best Practices
Apply Flexbox effectively with these guidelines:
- Understand the main axis and cross axis before using alignment properties — justify-content operates along the main axis (row direction in flex-direction: row), while align-items operates along the cross axis
- Use the flex shorthand rather than setting flex-grow, flex-shrink, and flex-basis separately — flex: 1 is shorthand for flex: 1 1 0, which creates equally growing items that start from zero base size
- Avoid setting both a fixed width and flex-grow on an item — flex-basis should be used to set the starting size, letting the browser's flex algorithm grow or shrink from there
- Use gap instead of margin for spacing between flex items — gap does not apply to the outer edges, making it easier to control container padding separately
- When items are not aligning as expected, check whether a parent element is also a flex container that might be overriding the expected layout behavior
Frequently Asked Questions
What is the difference between justify-content and align-items?
justify-content aligns flex items along the main axis (the direction of flex-direction — horizontal for row, vertical for column). align-items aligns them along the cross axis (perpendicular to flex-direction). Think of justify-content as horizontal alignment and align-items as vertical alignment when flex-direction is row.
What does flex: 1 actually mean?
flex: 1 is shorthand for flex-grow: 1; flex-shrink: 1; flex-basis: 0. This means the item will grow to fill available space (grow: 1), shrink if necessary (shrink: 1), and starts from a base size of 0 before growing. Multiple items with flex: 1 share the available space equally.
What is the difference between align-items and align-content?
align-items aligns items within a single flex line along the cross axis. align-content aligns multiple flex lines relative to each other when flex-wrap creates more than one line. align-content has no effect when all items are on a single line, which is the default when flex-wrap: nowrap is set.
How do I prevent flex items from shrinking below their content size?
Set flex-shrink: 0 on the item to prevent it from shrinking at all. Alternatively, set min-width: 0 on items that you want to allow to shrink below their content size — this overrides the default min-width: auto behavior that prevents content overflow from being clipped.
What is the order property and when should I use it?
The order property changes the visual order of flex items without changing the DOM order. Lower values appear first; the default is 0. Use it sparingly for purely visual reordering at specific breakpoints, but be aware that it creates a disconnect between visual and DOM order that can harm keyboard navigation and accessibility.
Can Flexbox handle two-dimensional layouts?
Flexbox is designed for one-dimensional layouts. With flex-wrap: wrap you can create multi-row layouts, but you cannot align items across rows the way CSS Grid can. For true two-dimensional alignment, use CSS Grid. A common pattern is to use Grid for the overall page layout and Flexbox for individual components within grid cells.
Does gap work in Flexbox in all browsers?
Yes. The gap property (and its longhand column-gap and row-gap) works in Flexbox in all modern browsers as of 2021. Safari added support in version 14.1. The old grid-gap shorthand still works but is considered deprecated in favor of the unprefixed gap.
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