FlexBox CSS Magic

One Rule to Rule them all

what is it?

The Flexbox Layout provides an efficient way to layout, align and distribute space among items.

 

A flex container expands items to fill available free space, or shrinks them to prevent overflow.

OH NO.

I still haven't Figured Out your

ANOTHER LAYOUT system?

display:inline-table-cell

VOODO!

Previous

the problem today:

With the growing demand to responsive, dynamic elements and complex designs, current methods are no longer cutting it.

floats, table-cell, text-align, margin:auto, vertical-align....

CSS is broken

centering nightmare

centering nightmare

Flexible components

justified headers

pinned at the bottom

dynamic length lists

holy grail layout

Still don't want flexbox?

Flexbox solves:

1. Items distribution

2. Items size

3. Items order

Basics

Flex Container

Flex Items

Main Axis

Cross Axis

so simple now:

Quick centering

Equal distribution

.container {
  display: flex;
  justify-content: center;
  align-items: center;
}
.container {
  display: flex;
}
input {
  flex: 1;
}

So simple!

Flex container

.container {
    display: flex;
}

The container controls the distribution and flow

of its children.

When setting an element as a flex container, it automatically sets its children as flex items.

Flex container - props

justify-content  How the items are aligned horizontally
 

align-items  How the items are aligned vertically

flex-direction  Which direction the items are flowing

 

flex-wrap  Should the items wrap to more than one line
 

align-content  If wrapped - alignment of wrapped lines

Flex container - justify

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

Use justify-content to sort the items along the main axis.

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

Flex container - ALIGN

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

Use align-items to sort the items along the cross axis.

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

flex container - flow

.container {
    flex-wrap: wrap;
}

Use flex-wrap to determine how items wrap to next line.

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

Use flex-direction to set row, column, or reversed order.

CONTAINER - SUMMARY

container - playground

Flex items

.antman {
    width: 35px;
}
.spiderman {
    flex: 1;
}
.the-hulk {
    flex: 3;
}

Each item controls its own size and order, and in some cases defines its location.

Flex item - props

flex  How the item will grow/shrink when there is free space
 

align-self  How this specific item will be aligned

order  What will be the order of this item within the children

 

margin  When auto - takes up all free space

flex item - props

align-self - Aligns the item itself, regardless of container

margin - When set to "auto" - it pins the element to one of the sides.

order - Determines the order of the element

.item:nth-child(3) {
  order: -1;
}
.item:nth-child(4) {
  align-self: flex-end;
}

Flex items - flex

.flex-item {
    flex: <flex-grow> <flex-shrink> <flex-basis>;
}

This is where flexbox gets flexible.

The flex container sums the sizes of all its children.

If any extra space is left, it is distributed between them according to flex-grow, flex-shrink and flex-basis.

flex-grow

how much the item will grow, relative to other items, if space is available
(default: 0)

flex-shrink

how much the item will shrink, relative to other items, if there is not enough space
(default: 1)

flex-basis

the initial starting size before space is distributed
(default: auto)

.flex-item {
    flex: 1 0 10px;
}

This means the item will start as 10px, cannot be shrinked, and it will get unit of extra space, if left.

Flex-grow

How much the flex item will grow relative to the rest of the flex items, when positive free space is distributed.

.item {
    flex-grow: 1;
}
.item {
    flex-grow: 1;
}

.item-2 {
    flex-grow: 3;
}

Flex-shrink

How much the flex item will shrink relative to the rest of the flex items, when negative free space is distributed.

.item {
    flex-shrink: 1;
}

.item-2 {
    flex-shrink: 0;
}

Initial size of the item, before all space calculations.
This is sort of "min-width". the browser will only go beneath it if there is no other option (no wrap, for example)

Flex-basis

the Flex shorthand

The W3C recommends always using the flex shorthand when possible. It can set other values correctly.

.item {
  flex: 2;
}
.item {
  flex: 2 1 0%;
}
.item {
  flex: 0 1 auto;
}
.item {
  /* no value */
}

the Flex cheatsheet

I want my item to be fully flexible

I want my item to start at a size, 
never grow, and shrink only if needed

I want my item to start at a size, grow freely, and shrink if needed

.item {
   flex: 1;
/* flex: 1 1 0%; */
}
.item {
   width: 50px;
/* flex: 0 1 auto; */
}
.item {
   flex: 50px;
/* flex: 1 1 50px; */
}

I want my item to be in a specific size!
Leave me out of this.

.item {
  width: 50px;
  flex: none;
}

the Flex shorthand

Example - flex by factor (flex-grow)

.item {
   flex: 1;
// flex: 1 1 0px;
}

.item:hover {
   flex: 2; 
// flex: 2 1 0px;
}

the Flex shorthand

Example - flex by size

.container {
   flex-wrap: wrap;
}

.item {
   flex: 30%;
// flex: 1 1 30%;
}

.item:hover {
   flex: 100%;
// flex: 1 1 100%;
}

Flex playground

Let's build a responsive component!

Common cases

1. Quick centering

.container {
  display: flex;
  justify-content: center;
  align-items: center;
}

2. Proportional distribution

.container {
  display: flex;
}
.item {
  flex: 1;
}

Common cases

3. Even spacing

4. Centered wrapping

.container {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-content: center;
}
.container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

Common cases

5. Decorated input

.wrapper{
  display: flex;
}
.input {
  /* Grow as needed, but never shrink so
     small that we can't read the placeholder */
  flex: 1 0 8em;
}
.submit {
  /* Never shrink or grow */
  flex: 0 0 auto;
}
.icon {
  /* Don't shrink or grow and use a default size */
  flex: 0 0 2.75em;
}

Common cases

6. Dynamic component

.container {
  display: flex;
  align-items: stretch;
}
.left {
  width: 50px;
  display: flex;
  flex-direction: column;
  justify-content: space-around;
}
.right {
  flex: 1;
}

Common cases

7. Pinned item

.container {
  display: flex;
  justify-content: space-around;
  align-items: stretch;
}
.column {
  display: flex;
  flex-direction: column;
}
.item:last-child {
  margin-top: auto;
}

Common cases

8. Form layout

.container {
  display: flex;
  align-items: stretch;
}
.column {
  flex: 1;
  display: flex;
  flex-direction: column;
}

Browser support

CANIUSE

autoprefixer

RESOURCES

playgrounds

That's all folks!

Liad Yosef @ Duda

ADvanced

Flex-basis problem

The remaining space is calculated according the all the flex-basis values of the children. When you need perfect proportion - use the flex shorthand or make sure it is 0.

.item {
    flex-grow: 1;
    flex-basis: 0;
}

.item-3 {
    flex-grow: 2;
}

flex-grow: 1

flex-grow: 1

flex-grow: 2

.item {
    flex-grow: 1;
    flex-basis: 10px;
}

.item-3 {
    flex-grow: 2;
}

No basis - perfect proportion

With basis - unexpected result

flex-grow: 1

flex-grow: 1

flex-grow: 2

10px+ 5px=15px

10px+ 5px=15px

10px+10px=20px

if 50px available

the Flex shorthand

The W3C recommends always using the flex shorthand when possible. It can set other values correctly.

.item {
  flex: 2;
}
.item {
  flex: 2 1 0%;
}
.item {
  flex: 30px;
}
.item {
  flex: 1 1 30px;
}
.item {
  flex: none;
}
.item {
  flex: 0 0 auto;
}
.item {
  flex: 0 1 auto;
}
.item {
  /* no value */
}

Flexbox

By Liad Yosef

Flexbox

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