Complete Guide to CSS Flexbox

Last Updated : 23 Jul, 2025

Flexbox, short for Flexible Box Layout, is a one-dimensional layout method for aligning and distributing space among items in a container. It allows you to design layouts that adapt to different screen sizes, making it ideal for responsive web design.

Flex Container: The parent element that holds flex items. The container becomes a flex container by setting the display property to flex or inline-flex.
Flex Items: The child elements within the flex container. Flexbox allows the flex items to grow, shrink, and adjust their sizes dynamically.
Main Axis: The primary axis along which the flex items are laid out (typically left-to-right or top-to-bottom).
Cross Axis: Perpendicular to the main axis, determining the vertical or horizontal alignment of the items.

HTML

<!--Driver Code Starts-->
<html>
<head>
<!--Driver Code Ends-->

    <style>
        .flex-container {
            display: flex;
            justify-content: space-between;
            background-color: #f0f0f0;
            padding: 10px;
        }

        .flex-item {
            background-color: #4CAF50;
            padding: 20px;
            color: white;
            width: 100px;
            text-align: center;
        }
    </style>

<!--Driver Code Starts-->
</head>
<body>
    <div class="flex-container">
        <div class="flex-item">Item 1</div>
        <div class="flex-item">Item 2</div>
        <div class="flex-item">Item 3</div>
    </div>
</body>
</html>
<!--Driver Code Ends-->

The .flex-container is set to display: flex, which makes it a flex container.
Inside the flex container, the items (.flex-item) are automatically arranged along the main axis.
The justify-content: space-between evenly spaces the items with space between them.

Flexbox Properties

Flexbox allows you to easily create flexible layouts that adjust to different screen sizes. With properties like display, flex-direction, and justify-content, you can control the arrangement of elements in rows or columns.

flexbox--complete-guide — Complete Guide to CSS Flexbox

Properties for the Parent or Children

The Flexbox Properties can be implemented to Parent element or the Child element, i.e. the various CSS Flex Properties can be applied to the flex container and the flex items.

flex container

Property	Descriptions	Syntax
display	Specifies the type of box used for an HTML element (block or inline).	.container { display: flex; }
flex-direction	Determines the primary axis direction for flex container layout.	.container { display: flex; flex-direction: row \| row-reverse \| column \| column-reverse; }
flex-wrap	Controls whether flex items are forced onto one line or can wrap onto multiple lines.	.container { display: flex; flex-wrap : nowrap \| wrap \| wrap-reverse; }
justify-content	Aligns flex items along the main axis, distributing space between or around them.	.container { display: flex; justify-content: flex-start \| flex-end \| center \| space-between \| space-around\| space-evenly; }
align-self	Overrides the default alignment for a specific flex item within the container.	.container{ align-self: center; }
align-items	Align flex items along the cross-axis within the container.	.container { align-items: stretch \| flex-start \| flex-end \| center \| baseline; }
align-content	Aligns lines of flex items along the cross-axis when multiple lines are present.	.container { display: flex; align-content: flex-start \| flex-end \| center \| space-between \| space-around \| stretch; }
flex-grow	Defines the ability of a flex item to grow proportionally within the flex container.	.item1 { flex-grow: 1; }
flex-shrink	Determines the ability of a flex item to shrink proportionally within the flex container.	.item { flex-shrink: 3; // default is 1 }
flex-basis	Specifies the initial size of a flex item along the main axis.	.item { flex-basis: <length> \| auto \| content; // default is auto }

display property

The display property in CSS defines how the components(div, hyperlink, heading, etc) are going to be placed on the web page. As the name suggests, this property is used to define the display of the different parts of a web page.

Property	Descriptions	Syntax
display: flex;	The property applies to the container, makes the container a block element, and enables a flex context for all its direct children	.container { display: flex; }
display: inline-flex;	The display: inline-flex; works in a similar way. It only creates a container that's an inline element.	.container { display: inline-flex; }

flex-direction property

The flex-direction is a CSS property that defines the primary axis of a flex container, determining the direction in which its flex items are placed.

Property	Descriptions	Syntax
row	Arrange items in a horizontal row, default direction.	flex-direction: row;
row-reverse	Arrange items in a horizontal row but in the reverse order.	flex-direction: row-reverse;
column	Arrange items in a vertical column.	flex-direction: column;
column-reverse	Arrange items in a vertical column but in the reverse order.	flex-direction: column-reverse;

flex-wrap property

The flex-wrap is a CSS property used in flex containers to control whether the flex items should wrap to a new line or stay on the same line.

Property	Descriptions	Syntax
wrap	Items are wrapped onto multiple lines, and arranged from top to bottom.	.container { display: flex; flex-wrap: wrap; }
nowrap	All flex items are arranged on a single line.	.container { display: flex; flex-wrap: nowrap; }
wrap-reverse	It repositions flex items onto multiple lines, wrapping from bottom to top.	.container { display: flex; flex-wrap: wrap-reverse; }

justify-content property

The justify-content is a CSS property in flex containers that aligns flex items along the main axis. It determines how extra space is distributed.

Property	Descriptions	Syntax
flex-start	Align items to the start of the container.	justify-content: flex-start;
flex-end	Align items to the end of the container.	justify-content: flex-end;
center	Centers items along the horizontal axis.	justify-content: center;
space-between	Items are evenly distributed with the first at the start and the last at the end.	justify-content: space-between;
space-around	Distributes items evenly with equal space around them.	justify-content: space-around;
space-evenly	Provides equal space around items, including at the start and end.	justify-content: space-evenly;

align-items property

The align-items is a CSS property used in flex containers to define how flex items align along the cross-axis.

Property	Descriptions	Syntax
stretch	Stretches items to fill the container along the cross-axis.	align-items: stretch;
flex-start	Align items to the start of the container cross-axis.	align-items: flex-start;
flex-end	Align items to the end of the container cross-axis.	align-items: flex-end;
center	Centers items along the container's cross-axis.	align-items: center;
baseline	Items are aligned to the baseline of the container.	align-items: baseline;

align-content property

The align-content is a CSS property applied to flex containers to control the alignment of lines along the cross axis when there's extra space.

Property	Descriptions	Syntax
stretch	Fills the available space, making lines stretch.	align-content: stretch;
flex-start	Packs lines at the start of the container.	align-content: flex-start;
flex-end	Packs lines at the end of the container.	align-content: flex-end;
center	Centers lines within the container.	align-content: center;
space-between	Evenly distributes lines, starting from the container's beginning to the end.	align-content: space-between;
space-around	Evenly distributes lines with equal space around them.	align-content: space-around;

The align-content property is effective when two criteria are fulfilled:

The flex container must have the wrap property applied, allowing flex items to wrap onto multiple lines.
The height of the flex container should exceed the height of the flex items' lines.

Properties for the Children (flex items)

The following are the list of properties that can be applied to the flex items.

Property	Descriptions	Syntax
order	Specifies the order in which the flex items appear within the container. Its default value is 0 and if value is -1 then it makes the last element to item element.	order: <integer>;
flex-grow	Determines the ability of a flex item to grow relative to others. It determines the ability of a flex item to grow relative to others.	flex-grow: <number>;
flex-shrink	Defines the ability of a flex item to shrink relative to others. The flex-shrink property won’t work if the flex container has the flex-wrap: wrap; property. The default value is 1. The value 0 allows keeping the item’s original size. Negative numbers are invalid. The flex property is the shorthand for flex-grow, flex-shrink, and flex-basis combined. Note: .item1 { flex: 1 1 20em; } // flex-grow, flex-shrink, and flex-basis	flex-shrink: <number>;
flex-basis	Establishes the initial size of a flex item. The "content" keyword flex-basis signifies sizing based on the item's content, while the "auto" keyword indicates that the size should be determined by the width or height property of the element, previously handled by the now-deprecated "main-size" keyword.	flex-basis: <length>
flex	Shorthand property combining flex-grow, flex-shrink, and flex-basis.	flex: none
align-self	Overrides the align-items value for a specific flex item.	align-self: auto

CSS Flex Responsive

In CSS Media Queries, you learned how to make your website look good on all sorts of screens and devices. By using media queries, you can create layouts that adjust nicely whether someone's using a big computer monitor or a small smartphone screen. It's like making sure your website looks awesome everywhere!

Syntax

.main {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    padding: 20px;
}
// Responsive layout - makes a one column
// layout instead of a three-column layout
@media (max-width: 768px) {
    main {
        flex-direction: column;
    }
}

image-(1)

Explanation:

Flexbox Layout: The <main> element uses display: flex to arrange sections in a flexible row layout. flex-wrap: wrap allows items to wrap to new lines when space is tight.
Responsive Design: A media query (@media (max-width: 768px)) changes the layout to a single-column direction on smaller screens.
Styling: The header and footer are styled with background colors, while each section has padding, borders, and margins for spacing and visual separation.

Benefits of Flexbox

Efficient Space Utilization: Flexbox automatically adjusts element sizes to use available space effectively, avoiding overcrowding or wasted space.
Centering Made Easy: Flexbox makes it simple to center elements both horizontally and vertically within their containers.
Sticky Footer: Flexbox helps create a footer that stays at the bottom of the page, providing a clean, professional look without unwanted gaps.
Flexible Navigation: Design menus that adapt to screen sizes, ensuring intuitive and visually appealing navigation structures.
Responsive Layouts: Flexbox allows elements to automatically adjust their size and layout for different screen sizes, ensuring a smooth user experience across devices.

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