CSS flex (aka "flexbox")

Flex allows us to position elements more easily and we should look at elements using this model as either a:

• flex container

• flex item

Flex containers

To make an element a flex container (also known as a wrapper), we would add display: flex in its CSS...

.flex-wpr {
    display: flex
}

...then apply it in its corresponding HTML tag:

<div class="flex-wpr">
<!-- this is now a flex container -->
</div>

inline-flex

Using display: inline-flex creates a container that won't take up the full width so elements can exist beside the container:

.flex-inline-wpr { 
    display: inline-flex
}

.non-flex-inline-wpr {
    display: inline
}

<div class="flex-inline-wpr">
    <!-- this is now a flex container -->
</div>

<div class="non-flex-inline-wpr">
    <!-- this can appear beside flex-wpr instead of under -->
</div>

Items within the container would still enjoy the flexbox layout!

Flex container properties

Aligning flex items with flex container properties

• justify-content (horizontal alignment)

  1. flex-start

  2. flex-end

  3. center

  4. space-around

  5. space-between

...
<div class="flex-wpr">
    <div class="flex-item">a</div>
    <div class="flex-item">b</div>
    <div class="flex-item">c</div>
</div>
...

.flex-item {
    justify-content: flex-end;
}

• align-items (vertical alignment for a single row)

  • flex-start

  • flex-end

  • center

• align-content (vertical alignment for the entire flex container)

  • flex-start (see align-items for diagram)

  • flex-end (see align-items for diagram)

  • center (see align-items for diagram)

  • space-around (see justify-content for diagram but vertically)

  • space-between (see justify-content for diagram but vertically)

Re-sizing flex items with flex container properties

• flex-grow (let the items grow for large window sizes)

  • positive numeric value x sets it to x times of its default grow size

• flex-shrink (let the items shrink for small window sizes)

  • positive numeric value x sets it to 1/x times of its the default grow size

  • a value of 0 shrinks the item to the smallest possible

• flex-basis (let the items grow/shrink with a limit)

  • positive numeric value + px

• flex (shorthand combining grow + shrink + basis)

  • flex: 2 1 150px means

    • flex-grow of 2

    • flex-shrink of 1

    • flex-basis of 150px

Arranging flex items with flex container properties

• flex-direction (arrangement of items)

  • row (items arranged from left to right, from the top left)

  • row-reverse (items arranged from right to left, from the top right)

  • column (items arranged from top to bottom, from the top left)

  • column-reverse (items arranged from bottom to top, from the bottom right)

• flex-wrap (let the items wrap to new lines)

  • wrap (wrap items into new line if there's no space)

  • wrap-reverse (same as wrap but reverse the item order)

  • nowrap (don't wrap)

• flex-flow (shorthand combining flex-direction and flex-wrap)

  • flex-flow: column wrap

    • flex-direction of column

    • flex-wrap of wrap

Flex items

To make a block element a flex item, simply include them into the already-defined flex container:

<div class="flex-wpr">
    <div>a</div>
    <div>b</div>
    <div>c</div>
</div>

We will notice that the flex items will appear inline by default, rather than the full-width of the default <div>

From there, we can align, re-size and arrange these flex items with ease!

Review

• setup

  • display: flex (make child divs inline)

  • display: flex-inline (make itself inline among other divs)

• alignment

  • justify-content (horizontal centering)

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

  • align-items (vertical centering of container's items)

    • flex-start, flex-end, center

  • align-content (vertical centering of entire container)

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

• resizing

  • flex-grow

  • flex-shrink

  • flex-basis

  • flex (shorthand for the above three properties)

• arrangement

  • flex-direction

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

  • flex-wrap

    • wrap, wrap-reverse, nowrap

  • flex-flow (shorthand for the above two properties)