CSS Grid Layout Module Level 1

Status: ED
ED: http://dev.w3.org/csswg/css-grid/
TR: http://www.w3.org/TR/css3-grid-layout/
Previous version: http://www.w3.org/TR/2013/WD-css3-grid-layout-20130402/
Previous version: http://www.w3.org/TR/2012/WD-css3-grid-layout-20121106/
Shortname: css-grid
Level: 1
Editor: Tab Atkins Jr., Google, http://www.xanthir.com/contact/
Editor: fantasai, Mozilla, http://fantasai.inkedblade.net/contact
Editor: Rossen Atanassov, Microsoft, ratan@microsoft.com
Previous editors: Alex Mogilevsky, Microsoft Corporation
Previous editors: Phil Cupp, Microsoft Corporation
Issues list: In Bugzilla
Abstract: This CSS module defines a two-dimensional grid-based layout system, optimized for user interface design. In the grid layout model, the children of a grid container can be positioned into arbitrary slots in a flexible or fixed predefined layout grid.
Ignored Terms: column-*, justify-*, containing block, , indefinite, block-start, block-end, inline-start, inline-end, end, max-content, grid-field, auto
Link Defaults: css21 (property) margin

Introduction and Overview

Grid layout contains features targeted at web application authors. The grid can be used to achieve many different layouts. It excels at dividing up space for major regions of an application, or defining the relationship in terms of size, position, and layer between parts of a control built from HTML primitives.

Like tables, grid layout enables an author to align elements into columns and rows, but unlike tables, grid layout doesn't have content structure, and thus enables a wide variety of layouts not possible with tables. For example, the children of a grid container can position themselves such that they overlap and layer similar to positioned elements.

In addition, the absence of content structure in grid layout helps to manage changes to layout by using fluid and source order independent layout techniques. By combining media queries with the CSS properties that control layout of the grid container and its children, authors can adapt their layout to changes in device form factors, orientation, and available space, without needing to alter the semantic nature of their content.

Background and Motivation

Application layout example requiring horizontal and vertical alignment.

As websites evolved from simple documents into complex, interactive applications, tools for document layout, e.g. floats, were not necessarily well suited for application layout. By using a combination of tables, JavaScript, or careful measurements on floated elements, authors discovered workarounds to achieve desired layouts. Layouts that adapted to the available space were often brittle and resulted in counter-intuitive behavior as space became constrained. As an alternative, authors of many web applications opted for a fixed layout that cannot take advantage of changes in the available rendering space on a screen.

The capabilities of grid layout address these problems. It provides a mechanism for authors to divide available space for layout into columns and rows using a set of predictable sizing behaviors. Authors can then precisely position and size the building block elements of their application by into grid areas defined by these columns and rows. Figure 1 illustrates a basic layout which can be achieved with grid layout.

Adapting Layouts to Available Space

Grid layout can be used to intelligently reflow elements within a webpage. Figure 2 represents a game with five major areas in the layout: the game title, stats area, game board, score area, and control area. The author's intent is to divide the space for the game such that:

• The stats area always appears immediately under the game title.
• The game board appears to the right of the stats and title.
• The top of the game title and the game board should always align.
• The bottom of the game board and the stats area align when the game has reached its minimum height, but otherwise the game board will stretch to take advantage of all the screen real-estate available to it.
• The score area should align into the column created by the game and stats area, while the controls are centered under the board.

As an alternative to using script to control the absolute position, width, and height of all elements, the author can use grid layout, as shown in Figure 3. The following example shows how an author might achieve all the sizing, placement, and alignment rules declaratively.

Note that there are multiple ways to specify the structure of the grid and to position and size grid items, each optimized for different scenarios. This example illustrates one that an author may use to define the position and space for each grid item using the 'grid-template-rows' and 'grid-template-columns' properties on the grid container, and the 'grid-row' and 'grid-column' properties on each grid item.

<style type="text/css">
  #grid {
    display: grid;

    /* Two columns: the first sized to content, the second receives
     * the remaining space, but is never smaller than the minimum 
     * size of the board or the game controls, which occupy this 
     * column. */
    grid-template-columns: auto minmax(min-content, 1fr);

    /* Three rows: the first and last sized to content, the middle 
     * row receives the remaining space, but is never smaller than 
     * the minimum height of the board or stats areas. */
    grid-template-rows: auto minmax(min-content, 1fr) auto
  }

  /* Each part of the game is positioned between grid lines by 
   * referencing the starting grid line and then specifying, if more 
   * than one, the number of rows or columns spanned to determine 
   * the ending grid line, which establishes bounds for the part. */
  #title    { grid-column: 1; grid-row: 1 }
  #score    { grid-column: 1; grid-row: 3 }
  #stats    { grid-column: 1; grid-row: 2; justify-self: start }
  #board    { grid-column: 2; grid-row: 1 / span 2; }
  #controls { grid-column: 2; grid-row: 3; align-self: center }
</style>

<div id="grid">
  <div id="title">Game Title</div>
  <div id="score">Score</div>
  <div id="stats">Stats</div>
  <div id="board">Board</div>
  <div id="controls">Controls</div>
</div>

Source Independence

Continuing the prior example, the author also wants the game to adapt to the space available on traditional computer monitors, handheld devices, or tablet computers. Also, the game should optimize the placement of the components when viewed either in landscape or portrait orientation (Figures 4 and 5). By combining grid layout with media queries, the author is able to use the same semantic markup, but rearrange the layout of elements independent of their source order, to achieve the desired layout in both orientations.

The following example leverages grid layout’s ability to name the space which will be occupied by a grid item. This allows the author to avoid rewriting rules for grid items as the grid’s definition changes.

<style type="text/css">
  @media (orientation: portrait) {
    #grid {
      display: grid;

      /* The rows, columns and areas of the grid are defined visually
       * using the grid-template-areas property.  Each string is a row, and
       * each word an area.  The number of words in a string 
       * determines the number of columns. Note the number of words 
       * in each string must be identical. */
      grid-template-areas: "title stats"
                           "score stats"
                           "board board"
                           "ctrls ctrls";

      /* Columns and rows created with the template property can be 
       * assigned a sizing function with the grid-template-columns 
       * and grid-template-rows properties. */
      grid-template-columns: auto minmax(min-content, 1fr);
      grid-template-rows: auto auto minmax(min-content, 1fr) auto
    }
  }

  @media (orientation: landscape) {
    #grid {
      display: grid;

      /* Again the template property defines areas of the same name, 
       * but this time positioned differently to better suit a 
       * landscape orientation. */
      grid-template-areas: "title board"
                           "stats board"
                           "score ctrls";

      grid-template-columns: auto minmax(min-content, 1fr);
      grid-template-rows: auto minmax(min-content, 1fr) auto
    }
  }

  /* The grid-area property places a grid item into a named 
   * region (area) of the grid. */
  #title    { grid-area: title }
  #score    { grid-area: score }
  #stats    { grid-area: stats }
  #board    { grid-area: board }
  #controls { grid-area: ctrls }
</style>

<div id="grid">
  <div id="title">Game Title</div>
  <div id="score">Score</div>
  <div id="stats">Stats</div>
  <div id="board">Board</div>
  <div id="controls">Controls</div>
</div>

Grid Layering of Elements

In the example shown in Figure 6, the author is creating a custom slider control. The control has six parts. The lower and upper labels align to the left and right edges of the control. The track of the slider spans the area between the labels. The lower and upper fill parts touch beneath the thumb, and the thumb is a fixed width and height that can be moved along the track by updating the two flex-sized columns.

Prior to the introduction of grid layout, the author would have likely used absolute positioning to control the top and left coordinates, along with the width and height of each HTML element that comprises the control. By leveraging grid layout, the author can instead limit script usage to handling mouse events on the thumb, which snaps to various positions along the track as the 'grid-template-columns' property of the grid container is updated.

<style type="text/css">
  #grid {
    display: grid;

    /* The grid-template-columns and rows properties also support 
     * naming grid lines which can then be used to position grid 
     * items.  The line names are assigned on either side of a column
     * or row sizing function where the line would logically exist. */
    grid-template-columns:
      (start)        auto
      (track-start)  0.5fr
      (thumb-start)  auto
      (fill-split)   auto
      (thumb-end)    0.5fr
      (track-end)    auto
      (end);
  }

  /* The grid-placement properties accept named lines. Below the
   * lines are referred to by name. Beyond any 
   * semantic advantage, the names also allow the author to avoid 
   * renumbering the grid-column-start and grid-row-start properties of the 
   * grid items.  This is similar to the concept demonstrated in the 
   * prior example with the grid-template-areas property during orientation 
   * changes, but grid lines can also work with layered grid items 
   * that have overlapping areas of different shapes like the thumb 
   * and track parts  in this example. */
  #lower-label { grid-column-start: start }
  #track       { grid-column: track-start / track-end; align-self: center }
  #upper-label { grid-column-end: end; }

  /* Fill parts are drawn above the track so set z-index to 5. */
  #lower-fill  { grid-column: track-start / fill-split; 
                 align-self: end; 
                 z-index: 5 }
  #upper-fill  { grid-column: fill-split / track-end; 
                 align-self: start; 
                 z-index: 5 }

  /* Thumb is the topmost part; assign it the highest z-index value. */
  #thumb       { grid-column: thumb-start / thumb-end; z-index: 10 }
</style>

<div id="grid">
  <div id="lower-label">Lower Label</div>
  <div id="upper-label">Upper Label</div>
  <div id="track">Track</div>
  <div id="lower-fill">Lower Fill</div>
  <div id="upper-fill">Upper Fill</div>
  <div id="thumb">Thumb</div>
</div>

Grid Layout Concepts and Terminology

In grid layout, the content of a grid container is laid out by positioning and aligning it into a grid. The grid is an intersecting set of horizontal and vertical grid lines that divides the grid container’s space into grid areas, into which grid items (representing the grid container’s content) can be placed. There are two sets of grid lines: one set defining columns that run along the block axis (the column axis, and an orthogonal set defining rows along the inline axis (the row axis). [[!CSS3-WRITING-MODES]]

Grid lines: Three in the block axis and four in the inline axis.

Grid Tracks and Cells

Grid track is a generic term for a grid column or grid row—in other words, it is the space between two adjacent grid lines. Each grid track is assigned a sizing function, which controls how wide or tall the column or row may grow, and thus how far apart its bounding grid lines are.

A grid cell is the similar term for the full grid—it is the space between two adjacent row and two adjacent column grid lines. It is the smallest unit of the grid that can be referenced when positioning grid items.

<style type="text/css">
	#grid {
		display: grid;
		grid-template-columns: 150px 1fr; /* two columns */
		grid-template-rows: 50px 1fr 50px /* three rows  */
	}
</style>

Grid Lines

Grid lines are the horizontal and vertical dividing lines of the grid. A grid line exists on either side of a column or row. They can be referred to by numerical index, or by an author-specified name. A grid item references the grid lines to determine its position within the grid using the grid-placement properties.

<style type="text/css">
  #grid {
    display: grid;
    grid-template-columns: 150px 1fr;
    grid-template-rows: 50px 1fr 50px
  }

  #item1 { grid-column: 2;
           grid-column-start: 1; grid-column-end: 1; }
</style>

<style type="text/css">
  /* equivalent layout to the prior example, but using named lines */
  #grid {
    display: grid;
    grid-template-columns: 150px (item1-start) 1fr (item1-end);
    grid-template-rows: (item1-start) 50px 1fr 50px (item1-end);
  }

  #item1 {
    grid-column: item1-start / item1-end;
    grid-row: item1-start / item1-end
  }
</style>

Grid Areas

A grid area is the logical space used to lay out one or more grid items. It is bound by four grid lines, one on each side of the grid area, and participates in the sizing of the grid tracks it intersects. A grid area can be named explicitly using the 'grid-template-areas' property of the grid container, or referenced implicitly by its bounding grid lines. A grid item is assigned to a grid area using the grid-placement properties.

<style type="text/css">
  /* using the template syntax */
  #grid  {
  display: grid;
  grid-template-areas: ". a"
                       "b a"
                       ". a";
  grid-template-columns: 150px 1fr;
  grid-template-rows: 50px 1fr 50px
  }

  #item1 { grid-area: a }
  #item2 { grid-area: b }
  #item3 { grid-area: b }

  /* Align items 2 and 3 at different points in the Grid Area "b".  */
  /* By default, Grid Items are stretched to fit their Grid Area    */
  /* and these items would layer one over the other. */
  #item2 { align-self: head }
  #item3 { justify-self: end; align-self: foot }
</style>

A grid item’s grid area forms the containing block into which it is laid out. Percentage lengths specified on a grid item resolve against this containing block. Percentages specified for 'margin-top', 'padding-top', 'margin-bottom', and 'padding-bottom' on a grid item resolve against the height of its containing block, rather than the width (as for blocks).

Grid items placed into the same grid area do not directly affect each other's layout. Indirectly, a grid item can affect the position of a grid line in a column or row that uses a contents-based relative size, which in turn can affect the position or size of another grid item.

Grid Layout Box Model

Grid Containers: the grid and ''inline-grid'' 'display' values

	Name: display
	New Values: grid | inline-grid
	

grid

This value causes an element to generate a block-level grid container box.

inline-grid

This value causes an element to generate an inline-level grid container box.

A grid container establishes a new grid formatting context for its contents. This is the same as establishing a block formatting context, except that grid layout is used instead of block layout: floats do not intrude into the grid container, and the grid container's margins do not collapse with the margins of its contents. Grid containers form a containing block for their contents exactly like block containers do. [[!CSS21]] The 'overflow' property applies to grid containers.

Grid containers are not block containers, and so some properties that were designed with the assumption of block layout don't apply in the context of grid layout. In particular:

• all of the 'column-*' properties in the Multicol module have no effect on a grid container.
• 'float' and 'clear' have no effect on a grid item. (However, the 'float' property still affects the computed value of 'display' on children of a grid container, as this occurs before grid items are determined.)
• 'vertical-align' has no effect on a grid item.
• the ''::first-line'' and ''::first-letter'' pseudo-elements do not apply to grid containers.

If an element's specified 'display' is ''inline-grid'' and the element is floated or absolutely positioned, the computed value of 'display' is grid. The table in CSS 2.1 Chapter 9.7 is thus amended to contain an additional row, with ''inline-grid'' in the "Specified Value" column and grid in the "Computed Value" column.

Grid Items

The contents of a grid container consists of zero or more grid items: each child of a grid container becomes a grid item, and each contiguous run of text that is directly contained inside a grid container is wrapped in an anonymous grid item. However, an anonymous grid item that contains only white space is not rendered, as if it were ''display:none''.

A grid item establishes a new formatting context for its contents. The type of this formatting context is determined by its 'display' value, as usual. The computed 'display' of a grid item is determined by applying the table in CSS 2.1 Chapter 9.7. However, grid items are grid-level boxes, not block-level boxes: they participate in their container's grid formatting context, not in a block formatting context.

<div style="display:grid">

	<!-- grid item: block child -->
	<div id="item1">block</div>

	<!-- grid item: floated element; floating is ignored -->
	<div id="item2" style="float: left;">float</div>

	<!-- grid item: anonymous block box around inline content -->
	anonymous item 3

	<!-- grid item: inline child -->
	<span>
		item 4
		<!-- grid items do not split around blocks -->
		<div id=not-an-item>item 4</div>
		item 4
	</span>
</div>

Some values of 'display' trigger the generation of anonymous boxes. For example, a misparented ''table-cell'' child is fixed up by generating anonymous ''table'' and ''table-row'' elements around it. [[!CSS21]] This fixup must occur before a grid container’s children are promoted to grid items. For example, given two contiguous child elements with ''display:table-cell'', an anonymous table wrapper box around them becomes the grid item.

Future display types may generate anonymous containers (e.g. ruby) or otherwise mangle the box tree (e.g. run-ins). It is intended that grid item determination run after these operations.

Absolutely-positioned Grid Children

An absolutely-positioned child element of a grid container does not participate directly in grid layout. Its static position is ???

The static position is affected by the alignment properties, as if it was a 0x0 thing floating around in the containing block. (Defaults to the start/start corner, since ''stretch'' can't do anything to it.)

If an absolutely positioned element's containing block is generated by a grid container, the grid-placement properties can be used to constrain it to a particular grid area, similar to how they affect regular grid items. In this case, an auto value for a grid-placement property indicates the corresponding padding edge of the grid container.

Absolute positioning can allow an element to “skip past” intervening grid containers, and resolve its grid-placement properties against a grid container other than its closest ancestor. However, as in other forms of CSS layout, elements that are absolutely-positioned to a grid container do not take up space or otherwise participate in the layout of the grid.

Collapsed Grid Items: the 'visibility' property

We want the ability to collapse grid tracks (similar to collapsing flex items or table rows/columns), but we're not sure exactly how to do it. Ideas welcome, please post them to the list.

Reordered Grid Items: the 'order' property

The 'order' property also applies to grid items. It affects their auto-placement and painting order.

The Explicit Grid

The three properties 'grid-template-rows', 'grid-template-columns', and 'grid-template-areas' together define the explicit grid of a grid container. The 'grid-template' property is a shorthand that sets all three at the same time. The final grid may end up larger due to grid items placed outside the explicit grid; in this case, any implicit tracks are sized by the 'grid-auto-rows' and 'grid-auto-columns' properties.

The size of the explicit grid is determined by the larger of the number of rows/columns defined by 'grid-template-areas' and the number of rows/columns sized by 'grid-template-rows'/'grid-template-columns'. Any rows/columns defined by 'grid-template-areas' but not sized by 'grid-template-rows'/'grid-template-columns' take their size from the 'grid-auto-rows'/'grid-auto-columns' properties.

Numeric indexes in the grid-placement properties count from the edges of the explicit grid, starting from 1. Positive indexes count from the before/start side, while negative indexes count from the after/end side.

Track Sizing: the 'grid-template-rows' and 'grid-template-columns' properties

	Name: grid-template-columns, grid-template-rows
	Value: none | <> | subgrid <>*
	Initial: none
	Applies to: grid containers
	Inherited: no
	Percentages: n/a
	Media: visual
	Computed value: As specified, except for auto (see prose)
	

These properties specify, as a space-separated track list, the line names and track sizing functions of the grid. Each sizing function can be specified as a length, a percentage of the grid container’s size, a measurement of the contents occupying the column or row, or a fraction of the free space in the grid. It can also be specified as a range using the ''minmax()'' notation, which can combine any of the previously mentioned mechanisms to define a min and max size for the column or row.

The 'grid-template-columns' property specifies the track list for the grid's columns, while 'grid-template-rows' specifies the track list for the grid's rows. The syntax of a track list is:

		<track-list>    = [ <>? [ <> | <> ] ]+ <>?
		<track-size>    = minmax( <> , <> ) | auto | <>
		<track-breadth> = <> | <> | <> | min-content | max-content
		<line-names>    = ( <>* )
	

Where:

<>

A non-negative length, as defined by CSS3 Values. [[!CSS3VAL]]

<>

A non-negative percentage, as defined by CSS3 Values. [[!CSS3VAL]] <> values are relative to the measure (logical width) of the grid container in column grid tracks, and the extent (logical height) of the grid container in row grid tracks. If the measure or extent of the grid container is an indefinite size, <> values relative to that size are treated as auto.

<>

A non-negative dimension with the unit "fr". Each <> value takes a share of the remaining space in proportion to its value. See Flexible Lengths for more details.

max-content

Represents the largest max size contribution of the grid items occupying the grid track.

min-content

Represents the largest min size contribution of the grid items occupying the grid track.

minmax(min, max)

Defines a size range greater than or equal to min and less than or equal to max. If max < min, then max is ignored and ''minmax(min,max)'' is treated as min.

auto

Computes to ''minmax(min-content, max-content)''.

The none value indicates that there is no explicit grid; any rows/columns will be implicitly generated, and their size will be determined by the 'grid-auto-rows' and 'grid-auto-columns' properties.

The subgrid value indicates that the grid will align to its parent grid in that axis. Rather than specifying the sizes of rows/columns explicitly, they'll be taken from the parent grid's definition. If the grid container is not a grid item, this value computes to none. See the Subgrids section for more detail.

grid-template-columns: 100px 1fr max-content minmax(min-content, 1fr);

/* examples of valid track definitions */
grid-template-rows: 1fr minmax(min-content, 1fr);
grid-template-rows: 10px repeat(2, 1fr auto minmax(30%, 1fr));
grid-template-rows: calc(4em - 5px)

Named Grid Lines: the ''(<>*)'' syntax

While grid lines can always be referred to by their numerical index, named lines can make the grid-placement properties easier to understand and maintain. Lines can be explicitly named in the 'grid-template-rows' and 'grid-template-columns' properties, or implicitly named by creating named grid areas with the 'grid-template-areas' property.

For example, the following code gives meaningful names to all of the lines in the grid. Note that some of the lines have multiple names.

<style>
  #grid {
    display: grid;
    grid-template-columns: (first nav) 150px (main) 1fr (last);
    grid-template-rows: (first header) 50px (main) 1fr (footer) 50px (last);
  }
</style>

Named Grid Lines.

Repeating Rows and Columns: the ''repeat()'' notation

The ''repeat()'' notation represents a repeated fragment of the track list. This is just a syntactic shorthand that allows writing a large number of columns or rows that exhibit a recurring pattern in a more compact form. The syntax of the ''repeat()'' notation is:

repeat() = repeat( <> , [ <>? <> ]+ <>? )

The first argument specifies the number of repetitions. The second argument is a track list, which is repeated that number of times. The ''repeat()'' notation cannot be nested; doing so makes the declaration invalid.

<style>
  #grid {
    display: grid;
    grid-template-columns: 10px (col-start) 250px (col-end) 
                           10px (col-start) 250px (col-end) 
                           10px (col-start) 250px (col-end) 
                           10px (col-start) 250px (col-end) 10px;
    grid-template-rows: 1fr;
  }

  /* Equivalent definition. */
  #grid {
    display: grid;
    grid-template-columns: repeat(4, 10px (col-start) 250px (col-end)) 10px;
    grid-template-rows: 1fr;
  }
</style>

Flexible Lengths: the ''fr'' unit

A flexible length or <> is a dimension with the ''fr'' unit, which represents a fraction of the free space in the grid container.

The distribution of free space occurs after all non-flexible sizing functions have reached their maximum. The total size of such rows or columns is subtracted from the available space, yielding the free space, which is then divided among the flex-sized rows and columns in proportion to their flex factor.

Flexible lengths in a track list work similarly to flexible lengths with a zero base size in [[CSS3-FLEXBOX]].

Each column or row's share of the free space can be computed as the column or row's <flex> * <free space> / <sum of all flex factors>. For the purpose of this calculation, a flexible length in the min position of a ''minmax()'' function is treated as ''0'' (an inflexible length).

When the available space is infinite (which happens when the grid container’s width or height is indefinite), flex-sized grid tracks are sized to their contents while retaining their respective proportions. The used size of each flex-sized grid track is computed by determining the 'max-content' size of each flex-sized grid track and dividing that size by the respective flex factor to determine a hypothetical 1fr size. The maximum of those is used as the ''1fr'' length, which is then multiplied by each grid track’s flex factor to determine its final size.

Subgrids: the subgrid keyword

A grid item can itself be a grid container by giving it ''display: grid''; in this case the layout of its contents will be independent of the layout of the grid it participates in.

In some cases it might be necessary for the contents of multiple grid items to align to each other. A grid container that is itself a grid item can defer the definition of its rows or columns to its parent grid container by using the subgrid keyword in 'grid-template-rows' and/or 'grid-template-columns', making it a subgrid in that dimension. In this case, the grid items of the subgrid participate in sizing the grid of the parent grid container, allowing the contents of both grids to align.

A subgrid behaves just like a normal grid container except that:

• The number of explicit tracks is given by its grid span, rather than by 'grid-template-rows'/'grid-template-columns'. If the grid has an automatic grid span, the number of tracks is determined by the size of the subgrid’s implicit grid.
• The grid-placement properties of the subgrid’s grid items are scoped to the lines covered by the subgrid. E.g., numeric indices count starting from the first line of the subgrid rather than the first line of the parent grid.
• The subgrid's own grid items participate in the sizing of its parent grid and are aligned to it. In this process, the sum of the item's margin, padding, and borders are applied as an extra layer of margin to the items at those edges.
• The subgrid is always stretched; the 'align-self'/'justify-self' properties on it are ignored. Any specified width/height constraints are also ignored.
• The subgrid’s explicit grid is always aligned with the corresponding section of the parent grid; the 'align-content'/'justify-content' properties on it are ignored.
• Explicit named lines can also be specified together with the subgrid keyword; these names apply to the corresponding lines taken from the parent grid. If the subgrid has an explicit grid span, any names for lines beyond the span are ignored. If the subgrid has an explicit grid position as well as an explicit grid span, it also automatically receives the names of the lines that it covers in its parent grid.

<ul>
  <li><label>Name:</label> <input name=fn>
  <li><label>Address:</label> <input name=address>
  <li><label>Phone:</label> <input name=phone>
</ul>

ul {
	display: grid;
	grid-auto-flow: rows;
	grid-template-columns: auto 1fr;
}
li {
	display: subgrid;
	margin: 0.5em;
	border: solid;
	padding: 0.5em;
}
label {
	grid-column: 1;
}
input {
	grid-column: 2;
}

Do we want to allow ''repeat()'' when specifying named lines for subgrids?

Resolved Values

The resolved value of the 'grid-template-rows' and 'grid-template-columns' properties is the used value, serialized as follows:

• Every track listed, whether implicitly or explicitly created.
• Every track size given as a length in pixels, regardless of sizing function.
• A contiguous run of two or more tracks that have the same size and associated line names may be serialized with the ''repeat()'' notation.

<style>
  #grid {
    width: 500px;
    grid-template-columns:
      (a)     auto
      (b)     minmax(min-content, 1fr)
      (b c d) repeat(2, (e) 40px)
              repeat(5, auto);
  }
</style>
<div id="grid">
  <div style="grid-column-start:1; width:50px"></div>
  <div style="grid-column-start:9; width:50px"></div>
</div>
<script>
  var gridElement = document.getElementById("grid");
  getComputedStyle(gridElement).gridDefinitionColumns;
  // (a) 50px (b) 320px (b c d) repeat(2, (e) 40px) repeat(4, 0px) 50px
</script>

In general, resolved values are the computed values, except for a small list of legacy 2.1 properties. Do we really want these properties to return the used value here? Bug about this.

Named Areas: the 'grid-template-areas' property

	Name: grid-template-areas
	Value: none | <>+
	Initial: none
	Applies to: grid containers
	Inherited: no
	Percentages: n/a
	Media: visual
	Computed value: specified value
	

This property specifies named grid areas, which are not associated with any particular grid item, but can be referenced from the grid-placement properties. The syntax of the 'grid-template-areas' property also provides a visualization of the structure of the grid, making the overall layout of the grid container easier to understand.

Values have the following meanings:

none

The grid container doesn't define any named grid areas.

<>+

A row is created for every separate string listed for the 'grid-template-areas' property, and a column is created for each identifier or period ("." U+002E) in the string, when the string's contents are parsed as CSS.

• A period represents an unnamed area in the grid container.
• An identifier creates a named grid area with the identifier as its name. Multiple identical identifiers create a single named grid area that spans the corresponding grid cells.

All strings must have the same number of columns, or else the declaration is invalid. If a named grid area spans multiple grid cells, but those cells do not form a single filled-in rectangle, the declaration is invalid. If a string's contents, when parsed as CSS, contain anything other than whitespace, identifiers, or periods, the declaration is invalid.

Non-rectangular or disconnected regions may be permitted in a future version of this module.

<style type="text/css">
  #grid {
    display: grid;
    grid-template-areas: "head head"
                         "nav  main"
                         "foot .   "
  }
  #grid > header { grid-area: head; }
  #grid > nav    { grid-area: nav; }
  #grid > main   { grid-area: main; }
  #grid > footer { grid-area: foot; }
</style>

Implicit Named Lines

The 'grid-template-areas' property creates implicit named lines from the named grid areas in the template. For each named grid area foo, four implicit named lines are created: two named ''foo-start'', naming the row-start and column-start lines of the named grid area, and two named ''foo-end'', naming the row-end and column-end lines of the named grid area.

These named lines behave just like any other named line, except that they do not appear in the value of 'grid-template-rows'/'grid-template-columns'. Even if an explicit line of the same name is defined, the implicit named lines are just more lines with the same name.

Grid Definition Shorthand: the 'grid-template' property

	Name: grid-template
	Value: none | <<'grid-template-columns'>> / <<'grid-template-rows'>> |
 [ <> / ]? [ <>? <> [ <> <> ]? ]+
	Initial: see individual properties
	Applies to: grid containers
	Inherited: see individual properties
	Percentages: see individual properties
	Media: visual
	Computed value: see individual properties
	

The 'grid-template' property is a shorthand for setting 'grid-template-columns', 'grid-template-rows', and 'grid-template-areas' in a single declaration. It has three distinct syntax forms:

none

Sets all three properties to their initial values (none).

<<'grid-template-columns'>> / <<'grid-template-rows'>>

Sets 'grid-template-columns' and 'grid-template-rows' to the specified values, respectively, and sets 'grid-template-areas' to none.

grid-template: auto 1fr auto / auto 1fr;

is equivalent to

grid-template-columns: auto 1fr auto;
grid-template-rows: auto 1fr;
grid-template-areas: none;

[ <> / ]?
[ <>? <> [ <> <> ]? ]+

• Sets 'grid-template-columns' to the track listing specified before the slash (or none, if not specified).
• Sets 'grid-template-areas' to the strings listed after the slash.
• Sets 'grid-template-rows' to the <>s following each string (filling in auto for any missing sizes), and splicing in the named lines defined before/after each size.

This syntax allows the author to align track names and sizes inline with their respective grid areas.

grid-template: auto 1fr auto / 
  (header-top) "a   a   a"     (header-bottom)
    (main-top) "b   b   b" 1fr (main-bottom);

is equivalent to

grid-template-columns: auto 1fr auto;
grid-template-rows: (header-top) auto (header-bottom main-top) 1fr (main-bottom);
grid-template-areas: "a a a" 
                     "b b b";

The Implicit Grid

While 'grid-template' and its longhand properties define the explicit grid, grid items can be positioned outside of these bounds. This causes the grid container to generate implicit grid tracks, forming the implicit grid. The 'grid-auto-rows' and 'grid-auto-columns' properties size these implicit grid tracks.

The 'grid-auto-flow' property controls auto-placement of grid items without an explicit position. Once the explicit grid is filled (or if there is no explicit grid) auto-placement will also cause the generation of implicit grid tracks. The 'grid-auto' shorthand can be used to set 'grid-auto-flow', 'grid-auto-rows', and 'grid-auto-columns' together.

Sizing Auto-generated Rows and Columns: the 'grid-auto-rows' and 'grid-auto-columns' properties

	Name: grid-auto-columns, grid-auto-rows
	Value: <>
	Initial: auto
	Applies to: grid containers
	Inherited: no
	Percentages: see Track Sizing
	Media: visual
	Computed value: see Track Sizing
	

If a grid item is positioned into a row or column that is not explicitly sized by 'grid-template-rows' or 'grid-template-columns', implicit grid tracks are created to hold it. This can happen either by explicitly positioning into a row or column that is out of range, or by the auto-placement algorithm creating additional rows or columns. The 'grid-auto-columns' and 'grid-auto-rows' properties specify the size of such implicitly-created tracks.

<style type="text/css">
	#grid { 
		display: grid; 
		grid-template-columns: 20px; 
		grid-template-rows: 20px }
	#A { grid-column: 1;          grid-row: 1; }
	#B { grid-column: 5;          grid-row: 1 / span 2; }
	#C { grid-column: 1 / span 2; grid-row: 2; }
</style>

<div id="grid">
	<div id="A">A</div>
	<div id="B">B</div>
	<div id="C">C</div>
</div>

Automatic Placement: the 'grid-auto-flow' property

	Name: grid-auto-flow
	Value: [ rows | columns ] && dense?
	Initial: rows
	Applies to: grid containers
	Inherited: no
	Percentages: n/a
	Media: visual
	Computed value: specified value
	

Grid items that aren't explicitly placed are are automatically placed into an unoccupied space in the grid container. The 'grid-auto-flow' property controls the direction in which the search for unoccupied space takes place, and whether rows or columns are added as needed to accommodate the content.

rows

The auto-placement algorithm places items by filling each row in turn, adding new rows as necessary.

columns

The auto-placement algorithm places items by filling each column in turn, adding new columns as necessary.

dense

If specified, the auto-placement algorithm uses a "dense" packing algorithm, which attempts to fill in holes in the grid if smaller items come up later. (By default, the auto-placement algorithm is "sparse", permanently skipping spaces that it can't fill with the curren grid item.) Note: This may cause items to appear out-of-order.

Add a value for stacking items on top of each other?

Add a value for flowing items together into a single slot?

Auto-placement takes grid items in 'order'-modified document order.

<style type="text/css">
  form {
    display: grid;
    /* Define three columns, all content-sized,
       and name the corresponding lines. */
    grid-template-columns: (labels) auto (controls) auto (oversized) auto;
    grid-auto-flow: rows;
  }
  form > label {
    /* Place all labels in the "labels" column and 
       automatically find the next available row. */
    grid-column: labels;
    grid-row: auto;
  }
  form > input, form > select {
    /* Place all controls in the "controls" column and 
       automatically find the next available row. */
    grid-column: controls;
    grid-row: auto;
  }

  #department {
    /* Auto place this item in the "oversized" column 
       in the first row where an area that spans three rows 
       won't overlap other explicitly placed items or areas 
       or any items automatically placed prior to this area. */
    grid-column: oversized;
    grid-row: span 3;
  }

  /* Place all the buttons of the form 
     in the explicitly defined grid area. */
  #buttons {
    grid-row: auto;

    /* Ensure the button area spans the entire grid element 
       in the row axis. */
    grid-column: 1 / -1;
    text-align: end;
  }
</style>
<form>
  <label for="firstname">First name:</label>
  <input type="text" id="firstname" name="firstname" />
  <label for="lastname">Last name:</label>
  <input type="text" id="lastname" name="lastname" />
  <label for="address">Address:</label>
  <input type="text" id="address" name="address" />
  <label for="address2">Address 2:</label>
  <input type="text" id="address2" name="address2" />
  <label for="city">City:</label>
  <input type="text" id="city" name="city" />
  <label for="state">State:</label>
  <select type="text" id="state" name="state">
    <option value="WA">Washington</option>
  </select>
  <label for="zip">Zip:</label>
  <input type="text" id="zip" name="zip" />

  <div id="department">
    <label for="department">Department:</label>
    <select id="department" name="department" multiple>
      <option value="finance">Finance</option>
      <option value="humanresources">Human Resources</option>
      <option value="marketing">Marketing</option>
    </select>
  </div>

  <div id="buttons">
    <button id="cancel">Cancel</button>
    <button id="back">Back</button>
    <button id="next">Next</button>
  </div>
</form>

Automatic Grid Item Placement Algorithm

The following summarizes the auto-placement algorithm for Grid items:

1. For each Grid item with a major-axis position that is not auto in source order:
   1. Resolve the auto value for its minor-axis position to the minimum value that ensures this item's grid area will not overlap the grid area of any explicitly or previously auto-placed item.
2. Determine the maximum number of minor tracks based on maximum track number implied by the 'grid-template-areas' property, the 'grid-template-rows' and 'grid-template-columns' properties, the position and size of any explicitly-defined grid items, or any minor-axis auto values resolved by the step 1 of the algorithm. Note that this step must be run prior to the layout algorithm.
3. The auto-placement cursor defines the current "insertion point" in the grid. Position the auto-placement cursor at position 1,1 in the grid.
4. For each grid item having an unresolved value of auto, in source order:
   1. If the minor-axis position is not auto, then:
      1. Set the minor-axis position of the cursor to be equal to the minor-axis position of the grid item.
      2. Increment the auto-placement cursor along the major-axis until a value is found where the grid item does not overlap the grid area of any other grid item (creating new major-axis tracks as necessary).
   2. If the minor and major-axis positions are both auto, then:
      1. Increment the minor-axis position of the auto-placement cursor until this item's grid area does not overlap another item's grid area, or causes the grid area to exceed the maximum number of minor-axis tracks previously determined in step 2.
      2. If this item's position is still unresolved after the previous step, then increment the cursor's major-axis position and reset the minor-axis position to 1 (creating new major-axis tracks if necessary).

Edit the algorithm to allow for dense packing.

Implicit Grid Shorthand: the 'grid-auto' property

	Name: grid-auto
	Value: <<'grid-auto-flow'>> || [ <<'grid-auto-columns'>> [ / <<'grid-auto-rows'>> ]? ]
	Initial: see individual properties
	Applies to: grid containers
	Inherited: see individual properties
	Percentages: see individual properties
	Media: visual
	Computed value: see individual properties
	

The 'grid-auto' property is a shorthand that sets all three of 'grid-auto-rows', 'grid-auto-columns', and 'grid-auto-flow' in a single declaration. If <<'grid-auto-rows'>> value is omitted, it is set to the value specified for 'grid-auto-columns'. Other omitted values are set to their initial values.

grid-auto-columns: 1fr;
grid-auto-rows: 1fr;
grid-auto-flow: rows;

grid-auto-columns: 1fr;
grid-auto-rows: auto;
grid-auto-flow: columns;

Placing Grid Items

Put in "common uses" section, like 'flex' has, to describe what you would use 'grid-area' for, etc.

Line-based Placement: the 'grid-row-start', 'grid-column-start', 'grid-row-end', and 'grid-column-end' properties

	Name: grid-row-start, grid-column-start, grid-row-end, grid-column-end
	Value: <>
	Initial: auto
	Applies to: grid items
	Inherited: no
	Percentages: n/a
	Media: visual
	Computed value: specified value (almost)
	

		<> = 
		  auto |
		  <> |
		  [ <> && <>? ] | 
		  [ span && [ <> || <> ] ]
	

			
1  2  3  4  5  6  7  8  9
+--+--+--+--+--+--+--+--+
|  |  |  |  |  |  |  |  |
A  B  C  A  B  C  A  B  C
|  |  |  |  |  |  |  |  |
+--+--+--+--+--+--+--+--+

grid-column-start: 4; grid-column-end: auto;
/* Line 4 to line 5 */

grid-column-start: auto; grid-column-end: 6;
/* Line 5 to line 6 */

grid-column-start: 'C'; grid-column-end: 'C';
/* Line 3 to line 9 */

grid-column-start: 'C'; grid-column-end: span 'C';
/* Line 3 to line 6 */

grid-column-start: span 'C'; grid-column-end: 'C';
/* Line 6 to line 9 */

grid-column-start: span 'C'; grid-column-end: span 'C';
/* Error: both properties compute to auto */

grid-column-start: 5; grid-column-end: 'C';
/* Line 5 to line 9 */

grid-column-start: 5; grid-column-end: span 'C';
/* Line 5 to line 6 */

grid-column-start: 8; grid-column-end: 8;
/* Error: line 8 to line 9 */

grid-column-start: 'B' 2; grid-column-end: span 1;
/* Line 5 to line 6 */

	Name: grid-column, grid-row
	Value: <> [ / <> ]?
	Initial: see individual properties
	Applies to: grid items
	Inherited: see individual properties
	Percentages: see individual properties
	Media: visual
	Computed value: see individual properties
	

	Name: grid-area
	Value: <> [ / <> ]{0,3}
	Initial: see individual properties
	Applies to: grid items
	Inherited: see individual properties
	Percentages: see individual properties
	Media: visual
	Computed value: see individual properties
	

TODO: provide example
		

<style type="text/css">
  #grid { 
    display: grid; 
    grid-template-columns: 1fr 1fr; 
    grid-template-rows: 1fr 1fr 
  }
  #A { grid-column: 1 / span 2; grid-row: 2; align-self: foot }
  #B { grid-column: 1; grid-row: 1; z-index: 10 }
  #C { grid-column: 2; grid-row: 1; align-self: head; margin-left: -20px }
  #D { grid-column: 2; grid-row: 2; justify-self: end; align-self: head }
  #E { grid-column: 1 / span 2; grid-row: 1 / span 2;
       z-index: 5; justify-self: center; align-self: center; }
</style>

<div id="grid">
  <div id="A">A</div>
  <div id="B">B</div>
  <div id="C">C</div>
  <div id="D">D</div>
  <div id="E">E</div>
</div>