CSS Grid

CoreUI for Bootstrap’s default grid system represents the culmination of over a decade of CSS layout techniques, tried and tested by millions of people. But, it was also created without many of the modern CSS features and techniques we’re seeing in browsers like the new CSS Grid.

CoreUI Bootstrap’s grid system uses a series of containers, rows, and columns to layout and align content. It’s built with flexbox and is fully responsive. Below is an example and an in-depth explanation for how the grid system comes together.

<div class="container">
  <div class="row">
    <div class="col">
      Column
    </div>
    <div class="col">
      Column
    </div>
    <div class="col">
      Column
    </div>
  </div>
</div>

The above example creates three equal-width columns across all devices and viewports using our predefined grid classes. Those columns are centered in the page with the parent .container.

How it works

With CoreUI 4, we’ve added the option to enable a separate grid system that’s built on CSS Grid, but with a CoreUI twist. You still get classes you can apply on a whim to build responsive layouts, but with a different approach under the hood.

• CSS Grid is opt-in. Disable the default grid system by setting $enable-grid-classes: false and enable the CSS Grid by setting $enable-cssgrid: true. Then, recompile your Sass.

• Replace instances of .row with .grid. The .grid class sets display: grid and creates a grid-template that you build on with your HTML.

• Replace .col-* classes with .g-col-* classes. This is because our CSS Grid columns use the grid-column property instead of width.

• Columns and gutter sizes are set via CSS variables. Set these on the parent .grid and customize however you want, inline or in a stylesheet, with --cui-columns and --cui-gap.

In the future, Bootstrap will likely shift to a hybrid solution as the gap property has achieved nearly full browser support for flexbox.

Key differences

Compared to the default grid system:

• Flex utilities don’t affect the CSS Grid columns in the same way.

• Gaps replaces gutters. The gap property replaces the horizontal padding from our default grid system and functions more like margin.

• As such, unlike .rows, .grids have no negative margins and margin utilities cannot be used to change the grid gutters. Grid gaps are applied horizontally and vertically by default. See the customizing section for more details.

• Inline and custom styles should be viewed as replacements for modifier classes (e.g., style="--cui-columns: 3;" vs class="row-cols-3").

• Nesting works similarly, but may require you to reset your column counts on each instance of a nested .grid. See the nesting section for details.

Examples

Three columns

Three equal-width columns across all viewports and devices can be created by using the .g-col-4 classes. Add responsive classes to change the layout by viewport size.

<div class="grid text-center">
  <div class="g-col-4">.g-col-4</div>
  <div class="g-col-4">.g-col-4</div>
  <div class="g-col-4">.g-col-4</div>
</div>

Responsive

Use responsive classes to adjust your layout across viewports. Here we start with two columns on the narrowest viewports, and then grow to three columns on medium viewports and above.

<div class="grid text-center">
  <div class="g-col-6 g-col-md-4">.g-col-6 .g-col-md-4</div>
  <div class="g-col-6 g-col-md-4">.g-col-6 .g-col-md-4</div>
  <div class="g-col-6 g-col-md-4">.g-col-6 .g-col-md-4</div>
</div>

Compare that to this two column layout at all viewports.

<div class="grid text-center">
  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>
</div>

Wrapping

Grid items automatically wrap to the next line when there’s no more room horizontally. Note that the gap applies to horizontal and vertical gaps between grid items.

<div class="grid text-center">
  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>

  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>
</div>

Starts

Start classes aim to replace our default grid’s offset classes, but they’re not entirely the same. CSS Grid creates a grid template through styles that tell browsers to “start at this column” and “end at this column.” Those properties are grid-column-start and grid-column-end. Start classes are shorthand for the former. Pair them with the column classes to size and align your columns however you need. Start classes begin at 1 as 0 is an invalid value for these properties.

<div class="grid text-center">
  <div class="g-col-3 g-start-2">.g-col-3 .g-start-2</div>
  <div class="g-col-4 g-start-6">.g-col-4 .g-start-6</div>
</div>

Auto columns

When there are no classes on the grid items (the immediate children of a .grid), each grid item will automatically be sized to one column.

<div class="grid text-center">
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
</div>

This behavior can be mixed with grid column classes.

<div class="grid text-center">
  <div class="g-col-6">.g-col-6</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
  <div>1</div>
</div>

Nesting

Similar to our default grid system, our CSS Grid allows for easy nesting of .grids. However, unlike the default, this grid inherits changes in the rows, columns, and gaps. Consider the example below:

• We override the default number of columns with a local CSS variable: --cui-columns: 3.
• In the first auto-column, the column count is inherited and each column is one-third of the available width.
• In the second auto-column, we’ve reset the column count on the nested .grid to 12 (our default).
• The third auto-column has no nested content.

In practice this allows for more complex and custom layouts when compared to our default grid system.

<div class="grid text-center" style="--cui-columns: 3;">
  <div>
    First auto-column
    <div class="grid">
      <div>Auto-column</div>
      <div>Auto-column</div>
    </div>
  </div>
  <div>
    Second auto-column
    <div class="grid" style="--cui-columns: 12;">
      <div class="g-col-6">6 of 12</div>
      <div class="g-col-4">4 of 12</div>
      <div class="g-col-2">2 of 12</div>
    </div>
  </div>
  <div>Third auto-column</div>
</div>

Customizing

Customize the number of columns, the number of rows, and the width of the gaps with local CSS variables.

These CSS variables have no default value; instead, they apply fallback values that are used until a local instance is provided. For example, we use var(--cui-rows, 1) for our CSS Grid rows, which ignores --cui-rows because that hasn’t been set anywhere yet. Once it is, the .grid instance will use that value instead of the fallback value of 1.

No grid classes

Immediate children elements of .grid are grid items, so they’ll be sized without explicitly adding a .g-col class.

<div class="grid text-center" style="--cui-columns: 3;">
  <div>Auto-column</div>
  <div>Auto-column</div>
  <div>Auto-column</div>
</div>

Columns and gaps

Adjust the number of columns and the gap.

<div class="grid text-center" style="--cui-columns: 4; --cui-gap: 5rem;">
  <div class="g-col-2">.g-col-2</div>
  <div class="g-col-2">.g-col-2</div>
</div>

<div class="grid text-center" style="--cui-columns: 10; --cui-gap: 1rem;">
  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-4">.g-col-4</div>
</div>

Adding rows

Adding more rows and changing the placement of columns:

<div class="grid text-center" style="--cui-rows: 3; --cui-columns: 3;">
  <div>Auto-column</div>
  <div class="g-start-2" style="grid-row: 2">Auto-column</div>
  <div class="g-start-3" style="grid-row: 3">Auto-column</div>
</div>

Gaps

Change the vertical gaps only by modifying the row-gap. Note that we use gap on .grids, but row-gap and column-gap can be modified as needed.

<div class="grid text-center" style="row-gap: 0;">
  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>

  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>
</div>

Because of that, you can have different vertical and horizontal gaps, which can take a single value (all sides) or a pair of values (vertical and horizontal). This can be applied with an inline style for gap, or with our --cui-gap CSS variable.

<div class="grid text-center" style="--cui-gap: .25rem 1rem;">
  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>

  <div class="g-col-6">.g-col-6</div>
  <div class="g-col-6">.g-col-6</div>
</div>

Sass

One limitation of the CSS Grid is that our default classes are still generated by two Sass variables, $grid-columns and $grid-gutter-width. This effectively predetermines the number of classes generated in our compiled CSS. You have two options here:

• Modify those default Sass variables and recompile your CSS.
• Use inline or custom styles to augment the provided classes.

For example, you can increase the column count and change the gap size, and then size your “columns” with a mix of inline styles and predefined CSS Grid column classes (e.g., .g-col-4).

<div class="grid text-center" style="--cui-columns: 18; --cui-gap: .5rem;">
  <div style="grid-column: span 14;">14 columns</div>
  <div class="g-col-4">.g-col-4</div>
</div>