CSS • Published June 15, 2026

CSS Flexbox Complete Guide: Properties, Alignment & Layouts

Learn CSS Flexbox layouts with this guide. Covers flex-direction, justify-content, align-items, flex-wrap, gap, and responsive box alignment patterns.

Master CSS Flexbox with clear examples for flex-direction, justify-content, align-items, flex-grow, and responsive layout patterns.

Frequently Asked Questions

Q1. What is CSS Flexbox?

CSS Flexible Box Layout (Flexbox) is a 1D layout model in CSS3 defined by W3C that distributes space along a single axis (row or column) and aligns items within a flex container.

Q2. What is the difference between justify-content and align-items?

justify-content aligns items along the Main Axis (horizontal in flex-direction: row). align-items aligns items along the perpendicular Cross Axis (vertical in flex-direction: row).

Q3. How do I center a div both horizontally and vertically with Flexbox?

Set the parent container to display: flex; justify-content: center; align-items: center; and ensure the container has an explicit height.

Q4. How does gap work in Flexbox?

The CSS gap property (e.g., gap: 16px;) sets spacing between flex items automatically without requiring margin adjustments on individual children.