Flexbox, short for Flexible Box Layout, is a modern layout model in CSS that makes it easy to design flexible, responsive layouts without using floats or positioning tricks. Whether you’re building a navbar, a card layout, or a mobile-first design, Flexbox is a must-know tool for web developers.

In this guide, you’ll learn everything about Flexbox — from syntax to real-world examples.

What is Flexbox?

Flexbox is a one-dimensional layout system, meaning it deals with layout in a single direction at a time — either as a row or a column.

✅ Use Flexbox for:

• Aligning items horizontally or vertically
• Creating space between elements
• Reordering items without changing the HTML
• Building responsive components

Flexbox Container vs. Items

When using Flexbox, you need two main parts:

• Flex container: the parent element
• Flex items: the direct children of the container

Example :

HTML:

<div class="flex-container">
  <div class="item">One</div>
  <div class="item">Two</div>
  <div class="item">Three</div>
</div>

CSS:

.flex-container {
  display: flex;
}

Main Properties of Flex Container

1. display: flex;

Turns the container into a Flexbox layout.

2. flex-direction

Defines the direction of main axis.

Value	Description
row	(default) Left to right
row-reverse	Right to left
column	Top to bottom
column-reverse	Bottom to top

css example:

.flex-container {
  flex-direction: row; /* horizontal layout */
}

3. justify-content

Controls horizontal alignment (main axis).

Value	Result
flex-start	Items align to the left
flex-end	Items align to the right
center	Items center horizontally
space-between	Equal space between items
space-around	Equal space around items
space-evenly	Equal spacing everywhere

.flex-container {
  justify-content: center;
}

4. align-items

Controls vertical alignment (cross axis).

Value	Description
stretch	(default) Fills height
flex-start	Aligns items to top
flex-end	Aligns items to bottom
center	Vertically centers
baseline	Aligns based on text baseline

css example :

.flex-container {
  align-items: center;
}

5. flex-wrap

By default, all items are in one line. Use this to wrap them.

.flex-container {
  flex-wrap: wrap;
}

Combine with :

.flex-container {
  flex-direction: row;
  flex-wrap: wrap;
}

/* or shorthand: */
.flex-container {
  flex-flow: row wrap;
}

Flex Item Properties

1. flex-grow

How much a flex item can grow relative to others.

.item {
  flex-grow: 1;
}

2. flex-shrink

How items shrink if the container is too small.

.item {
  flex-shrink: 1;
}

3. flex-basis

Initial size of the item before space distribution.

.item {
  flex-basis: 200px;
}

Combined Shorthand:

.item {
  flex: 1 0 200px; /* grow, shrink, basis */
}

4. align-self

Overrides align-items for a specific item.

.item {
  align-self: flex-end;
}

Responsive Layout Example Using Flexbox

<div class="flex-container">
  <div class="box">Box 1</div>
  <div class="box">Box 2</div>
  <div class="box">Box 3</div>
</div>

.flex-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
}

.box {
  flex: 1 1 250px;
  margin: 10px;
  background: #f1f1f1;
  padding: 20px;
  border-radius: 8px;
}

This layout:

• Is responsive
• Auto-wraps on small screens
• Adjusts box sizes dynamically

Common Flexbox Use Cases

• Centering a loader or button
• Navbar with logo on left and menu on right
• Equal-height cards
• Split-screen layout
• Footer alignment

Centering with Flexbox (Most Googled!)

Horizontally & Vertically center any element:

css:

.center {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

<div class="center">
  <h1>Hello, world!</h1>
</div>

Flexbox Gotchas

Mistake	Fix
margin: auto not working	Set a fixed width/height
Items not wrapping	Add flex-wrap: wrap
Items collapsing	Use flex-basis or min-width

Quick Flexbox Cheatsheet

display: flex;
flex-direction: row | column;
justify-content: flex-start | center | space-between;
align-items: stretch | center;
flex-wrap: wrap;
flex: grow shrink basis;
align-self: auto | flex-start | center;

This is all about Flexbox if you have any question comment below. Thanks