Free CSS Flexbox Generator – Build Layouts Visually

How Flexbox Works and How to Build a Layout

Flexbox is the CSS layout model for arranging items along a single line, either a row or a column, and distributing the leftover space between them. This generator gives you controls for the container properties, flex-direction, justify-content, align-items, flex-wrap and gap, with sample items rearranging live as you change each one. Front-end developers prototyping a navbar, anyone trying to centre a box vertically without remembering which property does it, and people learning the model for the first time all benefit from the same thing: seeing the effect before committing it to a stylesheet. My honest view is that flexbox is easier to learn by playing than by reading the specification. The concept everything hinges on is the two axes. flex-direction sets the main axis: with the default value row the main axis runs horizontally and the cross axis runs vertically; switch to column and the two swap over entirely. justify-content then distributes items along the main axis, offering values like flex-start, center, space-between and space-around, while align-items positions them along the cross axis with values including stretch, which is the default, center and baseline. That axis swap is why the same property does something completely different once you change direction, and it is the single most common source of flexbox confusion. flex-wrap decides whether items squeeze onto one line or spill onto a second, and gap adds spacing between them without the margin arithmetic that used to be necessary. Try a real case. To build a header with a logo on the left and navigation links pushed to the right, set display flex, flex-direction row, justify-content space-between and align-items center. The generated CSS is four declarations, and the preview shows the first item hard left, the last hard right, and both vertically centred within the container height. Now change flex-direction to column without touching anything else. space-between now distributes the items vertically, pushing them to the top and bottom edges of the container, and align-items center centres them horizontally instead. Nothing but the direction changed, yet the layout is unrecognisable, which demonstrates the axis rule far better than any diagram in a tutorial does. Concrete uses. A developer builds a card footer where a price sits left and a button sits right, using justify-content space-between in two lines of CSS instead of floats. Someone centring a loading spinner both ways uses justify-content center with align-items center, the modern replacement for a stack of absolute positioning hacks. A team building a tag list turns on flex-wrap and sets a gap so the chips reflow neatly on a narrow phone screen. A designer prototypes three pricing columns of equal height, which flexbox provides for free because align-items defaults to stretch. A developer pins a sticky footer to the bottom of a short page using a column layout. Two things worth knowing. Gap is the property people forget exists, and they add margins to children instead, which creates unwanted space at the ends and then needs a negative-margin fix on the parent; gap solves it in one line with no side effects. The pitfall that catches beginners is applying flex properties to the wrong element: justify-content and align-items belong on the container, while flex-grow, flex-shrink and flex-basis belong on the children, and setting a container property on a child does nothing at all. Also remember flexbox is one-dimensional by design, so if you need to align items in both rows and columns simultaneously, CSS Grid is the right tool instead. Flexbox needs no vendor prefixes in any current browser, so the generated declarations are safe to ship as they are. Everything runs in your browser and nothing is uploaded anywhere.

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