Introduction to

FlexBox

CSS Layouts I

Created by Kostas Minaidis

What is FlexBox?

According to the Specs:

A new layout mode, flex layout, optimized for user interface design. In the flex layout model, the children of a flex container can be laid out in any direction, and can “flex” their sizes, either growing to fill unused space or shrinking to avoid overflowing the parent.

How does it work?

display: flex;

Image: FlexBox by Codrops

Image: W3C

FlexBox Container/Parent Properties

display

This defines a flex container; inline or block depending on the given value. It enables a flex context for all its direct children (display: flex is acting on the first childs of the container, not its descendants.). 

									.container { display: flex; }
									.container { display: inline-flex; }

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Container/Parent Properties

flex-direction

flex-direction

This establishes the main-axis, thus defining the direction flex items are placed in the flex container. Flexbox is (aside from optional wrapping) a single-direction layout concept. Think of flex items as primarily laying out either in horizontal rows or vertical. 

								.container {
								   flex-direction: row;
								   flex-direction: row-reverse;
								   flex-direction: column;
								   flex-direction: column-reverse;
								}

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Container/Parent Properties

flex-wrap

flex-wrap

By default, flex items will all try to fit onto one line. You can change that and allow the items to wrap as needed with this property. 

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

Source: A Complete Guide to FlexBox

Interactive Demo Time
Demo
FlexBox Container/Parent Properties

flex-flow

This is a shorthand flex-direction and flex-wrap properties, which together define the flex container's main and cross axes. Default is row nowrap. 

								.container { 

								  flex-flow: <flex-direction> <flex-wrap>; 
								}

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Container/Parent Properties

justify-content

justify-content

This defines the alignment along the main axis. It helps distribute extra free space left over when either all the flex items on a line are inflexible, or are flexible but have reached their maximum size. It also exerts some control over the alignment of items when they overflow the line. 

								.container { justify-content: flex-start; }
								.container { justify-content: flex-end; }
								.container { justify-content: center; }
								.container { justify-content: space-between; }
								.container { justify-content: space-around; }
								.container { justify-content: space-evenly; }

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Container/Parent Properties

align-items

align-items

This defines the default behaviour for how flex items are laid out along the cross axis on the current line. Think of it as the justify-content version for the cross-axis (perpendicular to the main-axis). 


								.container { align-items: flex-start; }
								.container { align-items: flex-end; }
								.container { align-items: center; }
								.container { align-items: baseline; }
								.container { align-items: stretch; }

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Container/Parent Properties

align-content

align-content

This aligns a flex container's lines within when there is extra space in the cross-axis, similar to how justify-content aligns individual items within the main-axis. Note: this property has no effect when there is only one line of flex items. 


									.container { align-content: flex-start; }
									.container { align-content: flex-end; }
									.container { align-content: center; }
									.container { align-content: space-between; }
									.container { align-content: space-around; }
									.container { align-content: stretch; }

Source: A Complete Guide to FlexBox

Interactive Demo Time

align-items vs. align-content

Interactive Demo Time

Meet the Children...

...properties

FlexBox Item/Child Properties

order

order

By default, flex items are laid out in the source order. However, the order property controls the order in which they appear in the flex container. 


								.item { order: <integer>; }

								/* default is 0 */

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Item/Child Properties

flex-grow

flex-grow

This defines the ability for a flex item to grow if necessary. It accepts a unitless value that serves as a proportion. It dictates what amount of the available space inside the flex container the item should take up. If all items have flex-grow set to 1, the remaining space in the container will be distributed equally to all children. If one of the children has a value of 2, the remaining space would take up twice as much space as the others (or it will try to, at least). Negative numbers are invalid. 


								.item { flex-grow: <number> }
 								
 								/* default 0 */

Source: A Complete Guide to FlexBox

Interactive Demo Time

Use Case #1

FlexBox Item/Child Properties

flex-shrink

flex-shrink

This defines the ability for a flex item to shrink if necessary. Negative numbers are invalid. 


								.item { flex-shrink: <number> }
 								
 								/* default 1 */

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Item/Child Properties

flex-basis

flex-basis

This defines the default size of an element before the remaining space is distributed. It can be a length (e.g. 20%, 5rem, etc.) or a keyword. The auto keyword means "look at my width or height property". If set to 0, the extra space around content isn't factored in. If set to auto, the extra space is distributed based on its flex-grow value. 


								.item { flex-basis: <length> | auto; }

								/* default auto */

Source: A Complete Guide to FlexBox

Interactive Demo Time
FlexBox Item/Child Properties

flex

flex

This is the shorthand for flex-grow, flex-shrink and flex-basis combined. The second and third parameters (flex-shrink and flex-basis) are optional. Default is 0 1 auto.It is recommended that you use this shorthand property rather than set the individual properties. The short hand sets the other values intelligently. 


								.item { 

								flex: <flex-grow> <flex-shrink> <flex-basis>  

								}

Source: A Complete Guide to FlexBox

FlexBox Item/Child Properties

align-self

align-self

This allows the default alignment (or the one specified by align-items) to be overridden for individual flex items. Please see the align-items explanation to understand the available values. Note that float, clear and vertical-align have no effect on a flex item. 

								.item { align-self: auto; }
								.item { align-self: flex-start; }
								.item { align-self: flex-end; }
								.item { align-self: center; }
								.item { align-self: baseline; }
								.item { align-self: stretch; }

Source: A Complete Guide to FlexBox

Interactive Demo Time
Resources - Part I:

- FlexBox in 5 Minutes
- CSS-Tricks: A Complete Guide to Flexbox
- FlexBox Cheatsheet
- List of all FLEXBOX Layout properties
- CSS FlexBox YouTube Playlist by NetNinja
- UNDERSTANDING FLEXBOX: EVERYTHING YOU NEED TO KNOW
- FLEXBOX FROGGY
- FLEXBOX PLAYGROUND
- FLEXBOX CSS IN 20 MINUTES
- FlexBox by Codrops
- SOLVED BY FLEXBOX

Resources - Part II:

- How to Create a Flawless Responsive Post Grid with Flexbox
- The Complete Illustrated Flexbox Tutorial
- BASIC CONCEPTS OF FLEXBOX, MDN
- THE 4 (PRACTICAL) FLEXBOX TRICKS YOU NEED TO KNOW
- ALIGNING ITEMS IN A FLEX CONTAINER
- CREATE A MOBILE APP LAYOUT WITH FLEXBOX!, Wes Bos
- ORDERING FLEX ITEMS
- MASTERING WRAPPING OF FLEX ITEMS
- CONTROLLING RATIOS OF FLEX ITEMS ALONG THE MAIN AXIS
- TYPICAL USE CASES OF FLEXBOX

Resources - Part III:

- Flexbox — The Animated Tutorial
- The Complete CSS Flex Box Tutorial
- Scrimba: Learn Flexbox for free
- CSS FLEXBOX ESSENTIALS, DevTips
- FINALLY UNDERSTANDING FLEXBOX FLEX-GROW, FLEX-SHRINK AND FLEX-BASIS!
- WHAT ARE THE DIFFERENCES BETWEEN FLEX-BASIS AND WIDTH? [SO]
- DIVE INTO FLEXBOX
- CREATE A RESPONSIVE WEBPAGE WITH FLEXBOX
- AN EXERCISE USING CSS FLEXBOX | LEARN TO CREATE LAYOUTS USING CSS | LEARN CSS | FLEXBOX TUTORIAL
- HOW TO CREATE A RESPONSIVE NAVIGATION WITH FLEXBOX AND CSS GRID AND A NO JS DROPDOWN
- Building layouts with flexbox and CSS grids