[Sikom]

What is flexbox?
Flexbox is one of the newer layout modules in CSS. It initially got introduced in 2009, but got some major changes in 2011. The 2011 release is using mostly the same syntax as today. In the flexbox layout model the children are either laid out horizontally or vertically, and unused space can be assigned to specific children or get distrubuted between them. It is also possible to nest different orientations inside each other.

What does flexbox do?
The flexbox layout module makes it easier to design flexible responsive layout structures without using float, margin, padding or positioning.  The main idea behind the flex layout is to give a container the ability to alter its items' width/height (and order) to best fill the available space. A flex container can expand items to fill available free space, or shrinks them to prevent overflow.

Most importantly as mentioned earlier the flexbox layout is direction-agnostic as opposed to the regular layouts (block is vertical and inline which is horizontal)
How do I use flexbox?
Since flexbox is a whole module and not a single property, it involves a lot of things including its whole set of properties. Some of them are meant to be set on the container(parent element, known as "flex container"), while others are meant for it´s children (known as "flex items").

If regular layout is based on both block and inline flow directions, the flex layout is based on "flex-flow directions". Please have a look at this figure from the specification, explaining the main idea behind the flex layout.

Basically, items will be laid out following either the main axis (from main-start to main-end) or the cross axis (from cross-start to cross-end).
Main Axis: The main axis of a flex container is the primary axis along which flex items are laid out. It direction is based on the flex-direction property so it is not necessarily horizontal.

Main Start/End:  Flex items are placed within the container starting from main-start going to main-end.

Main Size:  A flex item's width or height, whichever is in the main dimension, is the item's main size.

Cross axis:  The axis perpendicular to the main axis is called the cross axis. Its direction depends on the main axis direction.

Cross start/end: Flex lines are filled with items and placed into the container starting on the cross-start side of the flex container and going toward the cross-end side.

Cross size: The width or height of a flex item, whichever is in the cross dimension, is the item's cross size.


Flex Container properties

display
This property defines a flex container; inline or block depending on the given value. It enables the flex context for all children.

Code:

.container {
   display: flex;
}

flex-direction

This establishes the main-direction, 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 laying either in horizontal rows or vertical columns.

Code:

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

   row (default): Left to right in ltr; right to left in rtl
   row-reverse: right to left in ltr; left to right in rtl
   column: same as row but top to bottom
   column-reverse: same as row-reverse but bottom to top


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.

Code:

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

   nowrap (default): All flex items will be on one line
   wrap: Flex items will wrap onto multiple lines, from top to bottom.
   wrap-reverse: Flex items will wrap onto multiple lines from bottom to top.


flex-flow (Applies to: parent flex container element)
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.

Code:

flex-flow: <‘flex-direction’> || <‘flex-wrap’>

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.

Code:

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

   

flex-start (default): items are packed toward the start line
   
flex-end: items are packed toward to end line
   
center: items are centered along the line
   
space-between: items are evenly distributed in the line; first item is on the start line, last item on the end line
   
space-around: items are evenly distributed in the line with equal space around them. Note that visually the spaces aren't equal, since all the items have equal space on both sides. The first item will have one unit of space against the container edge, but two units of space between the next item because that next item has its own spacing that applies.
   
space-evenly: items are distributed so that the spacing between any two items (and the space to the edges) is equal.

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).

Code:

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

 
flex-start: cross-start margin edge of the items is placed on the cross-start line
   
flex-end: cross-end margin edge of the items is placed on the cross-end line
   
center: items are centered in the cross-axis
   
baseline: items are aligned such as their baselines align
   
stretch (default): stretch to fill the container (still respect min-width/max-width)

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.

Code:

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

flex-start: lines packed to the start of the container
   
flex-end: lines packed to the end of the container
 
center: lines packed to the center of the container
   
space-between: lines evenly distributed; the first line is at the start of the container while the last one is at the end
   
space-around: lines evenly distributed with equal space around each line
   
stretch (default): lines stretch to take up the remaining space


Flex items properties

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.

Code:

.item {
 order: <integer>; /* default is 0 */
}

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).

Code:

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

Negative numbers are invalid.

flex-shrink
This defines the ability for a flex item to shrink if necessary.

Code:

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

Negative numbers are invalid.

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" (which was temporarily done by the main-size keyword until deprecated). The content keyword means "size it based on the item's content" - this keyword isn't well supported yet, so it's hard to test and harder to know what its brethren max-content, min-content, and fit-content do.

Code:

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

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. See this graphic.

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.

Code:

.item {
 flex: none | [ <'flex-grow'> <'flex-shrink'>? || <'flex-basis'> ]
}

It is recommended that you use this shorthand property rather than set the individual properties. The short hand sets the other values intelligently.

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.

Code:

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

Note that float, clear and vertical-align have no effect on a flex item.

Flexbox browser support
Broken up by "version" of flexbox
   (new) means the recent syntax from the specification (e.g. display: flex;) (This is the one we used)
   (tweener) means an odd unofficial syntax from 2011 (e.g. display: flexbox;)
   (old) means the old syntax from 2009 (e.g. display: box;)

Chrome:
20- (old)
21+ (new)

Safari:
3.1+ (old)
6.1+ (new)

Firefox:
2-21 (old)
22+ (new)

Opera:
12.1+ (new)

IE:
10 (tweener)
11+ (new)

Android:
2.1+ (old)
4.4+ (new)

IOS:
3.2+ (old)
7.1+ (new)

Blackberry browser 10+ supports the new syntax.

Please ask if there is anything you find confusing.
You guys showed some interest so might as well tag you @'Ender' and @'Bish0pQ' and @'mr.kurd'


Learn it better by trying this game:
Flexbox Froggy - http://flexboxfroggy.com/

[Mr.Kurd]

Thank you Sikom, Added to my bookmark list. very useful.

[Sikom]

Thank you Sikom, Added to my bookmark list. very useful.

Glad you found it useful, feel free to suggest other topics, and I might give it a shot.

[Blink]

That was a pretty good guide, bookmarked for use as reference.

This seems like it'll be useful in the future, thanks for this.

Now... If someone would do a WebASM guide...

[mothered]

Looking at the codes, they're pretty simple and very much self-explanatory.

I believe It has a lot to do with the way you've structured this thread, Inclusive of all supported Illustrations.
A job well done.

[Sikom]

That was a pretty good guide, bookmarked for use as reference.

This seems like it'll be useful in the future, thanks for this.

Now... If someone would do a WebASM guide...

Looking at the codes, they're pretty simple and very much self-explanatory.

I believe It has a lot to do with the way you've structured this thread, Inclusive of all supported Illustrations.
A job well done.

Thank you, glad you liked it

[Sikom]

@'ender' @'bish0pq' @'mr.kurd' and @'mothered'
Would you guys be interested in a tutorial on the new CSS Grid Layout. It is a 2-dimensional system, meaning it can handle both columns and rows, unlike flex-box which is mainly a 1-dimensional system.

That tutorial would be a bit longer than this one, so it will take quite a bit more work, hence me asking.

One thing that has to be noted is that CSS Grid Layout is so new that only newer versions support it.

Desktop
Chrome
57        

Opera
44        

Firefox
52
     
IE
11*

Edge
16      
 
Safari
10.1

*Supports the old syntax

Mobile / Tablet
iOS Safari
10.3

Opera Mobile
No

Opera Mini
No

Android
62

Android Chrome
64

Android Firefox
57

[mothered]

Would you guys be interested in a tutorial on the new CSS Grid Layout. It is a 2-dimensional system, meaning it can handle both columns and rows,

A guide on both columns and rows would be awesome.

I understand It's complexity and time consuming process, so absolutely no rush whatsoever.

[Sikom]

Would you guys be interested in a tutorial on the new CSS Grid Layout. It is a 2-dimensional system, meaning it can handle both columns and rows,

A guide on both columns and rows would be awesome.

I understand It's complexity and time consuming process, so absolutely no rush whatsoever.

I will consider making it. I am also considering making some beginner level tutorials about html and css

[Blink]

@'ender' @'bish0pq' @'mr.kurd' and @'mothered'
Would you guys be interested in a tutorial on the new CSS Grid Layout. It is a 2-dimensional system, meaning it can handle both columns and rows, unlike flex-box which is mainly a 1-dimensional system.

That tutorial would be a bit longer than this one, so it will take quite a bit more work, hence me asking.

One thing that has to be noted is that CSS Grid Layout is so new that only newer versions support it.

Desktop
Chrome
57        

Opera
44        

Firefox
52
     
IE
11*

Edge
16      
 
Safari
10.1

*Supports the old syntax

Mobile / Tablet
iOS Safari
10.3

Opera Mobile
No

Opera Mini
No

Android
62

Android Chrome
64

Android Firefox
57

Sure, I've looked into it a bit