float, flexbox

float

Usually, we position div in html which has various sections. This can be done alternatively using float attribute. We can float element to left,right,top & bottom as required.

In order to nullify float property, we need to use clear: left/right/both attributes.

flexbox - flexible box layout

Flexbox is layout module used for modern web development, it is flexible, and page size is adjusted as per device. 

• Flexbox is short for the Flexible Box Layout module.
• Flexbox is a layout method for arranging items in rows or columns.
• Flexbox makes it easier to design a flexible responsive layout structure, without using float or positioning.

A flexbox always consists of:

• a Flex Container - the parent (container) <div> element
• Flex Items - the items inside the container <div>

To start using CSS Flexbox, you need to first define a flex container.

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

.flex-container {
  display: flex;
}

The CSS properties we use for the flex container are:

• flex-direction
• flex-wrap
• flex-flow
• justify-content
• align-items
• align-content

The CSS flex-direction Property

The flex-direction property specifies the display-direction of flex items in the flex container.

The flex-direction property can have one of the following values:

• row
• column
• row-reverse
• column-reverse

Example

The row value is the default value, and it displays the flex items horizontally (from left to right):

.flex-container {
  display: flex;
  flex-direction: row;
}

Example

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

.flex-container {
  display: flex;
  flex-direction: column;
}

Example

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

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

Example

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

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

The CSS flex-wrap Property

The flex-wrap property specifies whether the flex items should wrap or not, if there is not enough room for them on one flex line.

The flex-wrap property can have one of the following values:

• nowrap
• wrap
• wrap-reverse

Example

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

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

Example

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

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

Example

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

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

The CSS flex-flow Property

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

Example

.flex-container {
  display: flex;
  flex-flow: row wrap;
}

The CSS justify-content Property

The justify-content property is used to align the flex items when they do not use all available space on the main-axis (horizontally).

The justify-content property can have one of the following values:

• center
• flex-start
• flex-end
• space-around
• space-between
• space-evenly

Example

The center value positions the flex items in the center of the container:

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

Example

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

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

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

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

Example

The space-around value displays the flex items with space around them:

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

Example

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

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

Example

The space-evenly value displays the flex items with equal space around them:

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

The CSS align-items Property

The align-items property is used to align the flex items when they do not use all available space on the cross-axis (vertically).

The align-items property can have one of the following values:

• center
• flex-start
• flex-end
• stretch
• baseline
• normal

In the following examples we use a 200 pixels high container, to better demonstrate the align-items property.

Example

The center value positions the flex items in the middle of the container:

.flex-container {
  display: flex;
  height: 200px;
  align-items: center;
}

Example

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

.flex-container {
  display: flex;
  height: 200px;
  align-items: flex-start;
}

Example

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

.flex-container {
  display: flex;
  height: 200px;
  align-items: flex-end;
}

Example

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

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

Example

The baseline value positions the flex items at the baseline of the container:

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

The CSS align-content Property

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

The align-content property is similar to align-items, but instead of aligning flex items, it aligns the flex lines.

The align-content property can have one of the following values:

• center
• stretch
• flex-start
• flex-end
• space-around
• space-between
• space-evenly

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

Example

With center, the flex lines are packed toward the center of the container:

.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: center;
}

Example

With stretch, the flex lines stretch to take up the remaining space of the container (this is default):

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

Example

With flex-start, the flex lines are packed toward the start of the container:

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

Example

With flex-end, the flex lines are packed toward the end of the container: 

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

Example

With space-between, the space between the flex lines are equal, but the first item is flush with the start edge of the container, and the last item is flush with the end edge of the container:

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

Example

With space-around, the space between the flex lines are equal, but the space before the first item and after the last item is set to half of the space between the flex lines:

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

Example

With space-evenly, the flex lines are evenly distributed in the flex container, with equal space on top, bottom and between:

.flex-container {
  display: flex;
  height: 600px;
  flex-wrap: wrap;
  align-content: space-evenly;
}

Perfect Centering

In the following example we will solve a 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:

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