Flexbox

Parent Element (Container)

Like we specified in the previous chapter, this is a flex container (the blue area) with three flex items:

The flex container becomes flexible by setting the display property to flex:

The flex container properties are:

• flex-direction

• flex-wrap

• flex-flow

• justify-content

• align-items

• align-content

The flex-direction Property

The flex-direction property defines in which direction the container wants to stack the flex items.

The column value stacks the flex items vertically (from top to bottom):

The column-reverse value stacks the flex items vertically (but from bottom to top):

The row-reverse value stacks the flex items horizontally (but from right to left):

The flex-wrap Property

The flex-wrap property specifies whether the flex items should wrap or not.

The wrap value specifies that the flex items will wrap if necessary:

The nowrap value specifies that the flex items will not wrap (this is default):

The wrap-reverse value specifies that the flexible items will wrap if necessary, in reverse order:

The flex-flow Property

The flex-flow property is a shorthand property for setting both the flex-direction and flex-wrap properties.

The justify-content Property

The justify-content property is used to align the flex items:

The center value aligns the flex items at the center of the container:

The flex-start value aligns the flex items at the beginning of the container (this is default):

The flex-end value aligns the flex items at the end of the container:

Example

The space-around value displays the flex items with space before, between, and after the lines:

Example

The space-between value displays the flex items with space between the lines:

The align-items Property

The align-items property is used to align the flex items.

The flex-start value aligns the flex items at the top of the container:

The flex-end value aligns the flex items at the bottom of the container:

Example

The stretch value stretches the flex items to fill the container (this is default):

// Some code
.flex-container {
  display: flex;
  height: 200px;
  align-items: stretch;
}

Example

The baseline value aligns the flex items such as their baselines aligns:

// Some code
.flex-container {
  display: flex;
  height: 200px;
  align-items: baseline;
}

Note: the example uses different font-size to demonstrate that the items gets aligned by the text baseline:

The align-content Property

The align-content property is used to align the flex lines.

In these examples we use a 600 pixels high container, with the flex-wrap property set to wrap, to better demonstrate the align-content property.

Example

The space-between value displays the flex lines with equal space between them:

// Some code
.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: space-between;
}

Example

The space-around value displays the flex lines with space before, between, and after them:

// Some code
.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: space-around;
}

Example

The stretch value stretches the flex lines to take up the remaining space (this is default):

// Some code
.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: stretch;
}

Example

The center value displays the flex lines in the middle of the container:

// Some code
flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: center;
}

Example

The flex-start value displays the flex lines at the start of the container:

// Some code
.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: flex-start;
}

Example

The flex-end value displays the flex lines at the end of the container:

// Some code
.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: flex-end;
}

Perfect Centering

In the following example we will solve a very common style problem: perfect centering.

SOLUTION: Set both the justify-content and align-items properties to center, and the flex item will be perfectly centered:

Example

// Some code
.flex-container {
  display: flex;
  height: 300px;
  justify-content: center;
  align-items: center;
}

The CSS Flexbox Container Properties

The following table lists all the CSS Flexbox Container properties:

Property	Description
align-content	Modifies the behavior of the flex-wrap property. It is similar to align-items, but instead of aligning flex items, it aligns flex lines
align-items	Vertically aligns the flex items when the items do not use all available space on the cross-axis
display	Specifies the type of box used for an HTML element
flex-direction	Specifies the direction of the flexible items inside a flex container
flex-flow	A shorthand property for flex-direction and flex-wrap
flex-wrap	Specifies whether the flex items should wrap or not, if there is not enough room for them on one flex line
justify-content	Horizontally aligns the flex items when the items do not use all available space on the main-axis