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CSS Grid Layout представляет двумерную сетку для CSS. Grid (здесь и далее подразумевается CSS Grid Layout ) можно использовать для размещения основных областей страницы или небольших элементов пользовательского интерфейса. В этой статье описывается компоновка сетки CSS и новая терминология, которая является частью спецификации CSS Grid Layout Level 1. Функции, показанные в этом обзоре, будут более подробно описаны в остальной части этого руководства.
Что такое Grid?
Grid представляет собой пересекающийся набор горизонтальных и вертикальных линий - один набор определяет столбцы, а другой строки. Элементы могут быть помещены в сетку, соответсвенно строкам и столбцам. Grid имеет следующие функции::
Фиксированные и гибкие размеры треков
Вы можете создать сетку с фиксированными размерами треков - например используя пиксели. Вы также можете создать сетку с гибкими размерами используя проценты или с новой единицей измерения fr, предназначенной для этой цели.
Расположение элемента
Вы можете размещать элементы в заданном месте Grid, используя номера строк, имена или путем привязки к области Grid. Grid также содержит алгоритм управления размещением элементов, не имеющих явной позиции в Grid.
Создание дополнительных треков для хранения контента
Вы можете определить явную сетку с макетом сетки, но спецификация также касается контента, добавленного за пределами объявленной сетки, при необходимости добавляя дополнительные строки и столбцы. Включены такие функции, как добавление «столько столбцов, сколько будет помещено в контейнер».
Управление выравниванием
Grid содержит функции выравнивания, чтобы мы могли контролировать, как элементы выравниваются после размещения в области сетки, и как выравнивается весь Grid.
Управление перекрывающимся контентом
В ячейку сетки может быть помещено более одного элемента, или области могут частично перекрывать друг друга. Затем это расслоение можно контролировать с помощью z-index.
Grid - это мощная спецификация и в сочетании с другими частями CSS, такими как flexbox, может помочь вам создать макеты, которые ранее невозможно было построить в CSS. Все начинается с создания сетки в вашем grid контейнере.
Grid контейнер
Мы создаем grid контейнер, объявляя display: grid или display: inline-grid на элементе. Как только мы это сделаем, все прямые дети этого элемента станут элементами сетки.
В этом примере, есть див содержащий класс wrapper с пятью потомками
<div class="wrapper"> <div>One</div> <div>Two</div> <div>Three</div> <div>Four</div> <div>Five</div> </div>
Сделаем wrapper grid контейнером
.wrapper {
display: grid;
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
Все прямые потомки теперь являются grid эелементами. В веб-браузере вы не увидите никакой разницы в отображении элементов, поскольку Grid создал единую сетку столбцов для элементов. На данный момент вам может оказаться удобным работать в Firefox Developer Edition, в котором есть Grid Inspector, доступный как часть инструментов разработчика. Если вы просмотрите этот пример в Firefox и проверите Grid, вы увидите маленький значок рядом с display: grid . Нажмите этот значок, и сетка на этом элементе будет наложена в окне браузера.
По мере вашего обучения и затем работы с CSS Grid Layout этот инструмент даст вам лучшее визуальное представление о том что происходит с вашей сеткой.
Если мы хотим чтобы это стало более похожим на сетку, нам нужно добавить треки столбцов.
Grid Tracks
We define rows and columns on our grid with the grid-template-columns and grid-template-rows properties. These define grid tracks. A grid track is the space between any two lines on the grid. In the below image you can see a track highlighter – the first row track in our grid.
I can add to our earlier example by adding the grid-template-columns property, then defining the size of the column tracks.
I have now created a grid with three 200-pixel-wide column tracks. The child items will be laid out on this grid one in each grid cell.
<div class="wrapper"> <div>One</div> <div>Two</div> <div>Three</div> <div>Four</div> <div>Five</div> </div>
.wrapper {
display: grid;
grid-template-columns: 200px 200px 200px;
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
The fr Unit
Tracks can be defined using any length unit. Grid also introduces an additional length unit to help us create flexible grid tracks. The new fr unit represents a fraction of the available space in the grid container. The next grid definition would create three equal width tracks that grow and shrink according to the available space.
<div class="wrapper"> <div>One</div> <div>Two</div> <div>Three</div> <div>Four</div> <div>Five</div> </div>
.wrapper {
display: grid;
grid-template-columns: 1fr 1fr 1fr;
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
In this next example, we create a definition with a 2fr track then two 1fr tracks. The available space is split into four. Two parts are given to the first track and one part each to the next two.
.wrapper {
display: grid;
grid-template-columns: 2fr 1fr 1fr;
}
In this final example, we mix absolute sized tracks with fraction units. The first track is 500 pixels so this fixed width is taken away from the available space. The remaining space is divided into three and assigned in proportion to the two flexible tracks.
.wrapper {
display: grid;
grid-template-columns: 500px 1fr 2fr;
}
Track listings with repeat() notation
Large grids with many tracks can use repeat() notation to repeat all or a section of the track listing. For example the grid definition:
.wrapper {
display: grid;
grid-template-columns: 1fr 1fr 1fr;
}
Can also be written as:
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
}
Repeat notation can be used for a part of the track listing. In this next example I have created a grid with an initial 20-pixel track, then a repeating section of 6 1fr tracks then a final 20-pixel track.
.wrapper {
display: grid;
grid-template-columns: 20px repeat(6, 1fr) 20px;
}
Repeat notation takes a track listing, therefore you can use it to create a repeating pattern of tracks. In this next example, my grid will consist of 10 tracks, a 1fr track followed by a 2fr track, repeated five times.
.wrapper {
display: grid;
grid-template-columns: repeat(5, 1fr 2fr);
}
The implicit and explicit grid
When creating our example grid we defined our column tracks with the grid-template-columns property, but let grid create rows as needed for the content. These rows are created in the implicit grid. The explicit grid consists of the rows and columns you define with grid-template-columns and grid-template-rows. If you place something outside of that defined grid, or due to the amount of content more grid tracks are needed, then grid creates rows and columns in the implicit grid. These tracks will be auto-sized by default, so will size based on the content inside them.
You can also define a set size for tracks created in the implicit grid with the grid-auto-rows and grid-auto-columns properties.
In the below example we use grid-auto-rows to ensure that tracks created in the implicit grid are 200 pixels tall.
<div class="wrapper"> <div>One</div> <div>Two</div> <div>Three</div> <div>Four</div> <div>Five</div> </div>
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
grid-auto-rows: 200px;
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
Track sizing and minmax()
When setting up an explicit grid or defining the sizing for automatically created rows or columns we may want to give tracks a minimum size, but ensure they expand to fit any content that is added. For example, I may want my rows to never collapse smaller than 100 pixels, but if my content stretches to 300 pixels in height I would like the row to stretch to that height.
Grid has a solution for this with the minmax() function. In this next example I am using minmax() in the value of grid-auto-rows. Automatically created rows will be a minimum of 100 pixels tall, and a maximum of auto. Using auto means that the size will look at the content size and so stretch to give space for the tallest thing in a cell in this row.
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
grid-auto-rows: minmax(100px, auto);
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
<div class="wrapper"> <div>One</div> <div>Two <p>I have some more content in.</p> <p>This makes me taller than 100 pixels.</p> </div> <div>Three</div> <div>Four</div> <div>Five</div> </div>
Grid Lines
It should be noted that when we define a grid we define the grid tracks, not the lines. Grid then gives us numbered lines to use when positioning items. In our three column, two row grid we have four column lines.
Lines are numbered according to the writing mode of the document. In a left-to-right language, line 1 is on the left-hand side of the grid. In a right-to-left language, it is on the right-hand side of the grid. Lines can also be named, and we will look at how to do this in a later guide in this series.
Positioning items against lines
We will be exploring line based placement in full detail in a later article, the following example demonstrates doing this in a simple way. When placing an item we target the line – rather than the track.
In the following example I am placing the first two items on our three column track grid, using the grid-column-start, grid-column-end, grid-row-start and grid-row-end properties. Working from left to right, the first item is placed against column line 1, and spans to column line 4, which in our case is the far right line on the grid. It begins at row line 1 and ends at row line 3, therefore spanning two row tracks.
The second item starts on grid column line 1, and spans one track. This is the default so I do not need to specify the end line. It also spans two row tracks from row line 3 to row line 5. The other items will place themselves into empty spaces on the grid.
<div class="wrapper"> <div class="box1">One</div> <div class="box2">Two</div> <div class="box3">Three</div> <div class="box4">Four</div> <div class="box5">Five</div> </div>
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
grid-auto-rows: 100px;
}
.box1 {
grid-column-start: 1;
grid-column-end: 4;
grid-row-start: 1;
grid-row-end: 3;
}
.box2 {
grid-column-start: 1;
grid-row-start: 3;
grid-row-end: 5;
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
Don't forget that you can use the Grid Inspector in Firefox Developer Tools to see how the items are positioned against the lines of the grid.
Grid Cells
A grid cell is the smallest unit on a grid, conceptually it is like a table cell. As we saw in our earlier examples, once a grid is defined on a parent the child items will lay themselves out once in each cell of the defined grid. In the below image I have highlighted the first cell of the grid.
Grid areas
Items can span one or more cells both by row or by column, and this creates a grid area. Grid areas have to be rectangular – it isn’t possible to create an L-shaped area for example. The highlighted grid area spans two row and two column tracks.
Gutters
Gutters or alleys between grid cells can be created using the grid-column-gap and grid-row-gap properties, or the shorthand grid-gap. In the below example I am creating a 10-pixel gap between columns and a 1em gap between rows.
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
grid-column-gap: 10px;
grid-row-gap: 1em;
}
<div class="wrapper"> <div>One</div> <div>Two</div> <div>Three</div> <div>Four</div> <div>Five</div> </div>
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.wrapper > div {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
Any space used by gaps will be accounted for before space is assigned to flexible length fr tracks, and gaps act for sizing purposes like a regular grid track, however you cannot place anything into a gap. In terms of line-based positioning, the gap acts like a fat line.
Nesting grids
A grid item can become a grid container. In the following example I have the three-column grid created earlier, with our two positioned items. In this case the first item has some sub-items. As these items are not direct children of the grid they do not participate in grid layout and so display in normal document flow.
<div class="wrapper">
<div class="box box1">
<div class="nested">a</div>
<div class="nested">b</div>
<div class="nested">c</div>
</div>
<div class="box box2">Two</div>
<div class="box box3">Three</div>
<div class="box box4">Four</div>
<div class="box box5">Five</div>
</div>
If I set box1 to display: grid I can give it a track definition and it too will become a grid, the items then lay out on this new grid.
.box1 {
grid-column-start: 1;
grid-column-end: 4;
grid-row-start: 1;
grid-row-end: 3;
display: grid;
grid-template-columns: repeat(3, 1fr);
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.box {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
In this case the nested grid has no relationship to the parent. As you can see in the example it has not inherited the grid-gap of the parent and the lines in the nested grid do not align to the lines in the parent grid.
Subgrid
In the level 1 grid specification there is a feature called subgrid which would let us create nested grids that use the track definition of the parent grid.
Subgrids are not yet implemented in any browsers, and the specification is subject to change.
In the current specification, we would edit the above nested grid example to use display: subgrid rather than display: grid, then remove the track definition. The nested grid will use the parent grid tracks to lay out items.
It should be noted that the nested grid is in both dimensions—rows and columns. There is no concept of the implicit grid working with subgrids. This means you need to ensure that the parent grid has enough row and column tracks for all the subitems.
.box1 {
grid-column-start: 1;
grid-column-end: 4;
grid-row-start: 1;
grid-row-end: 3;
display: subgrid;
}
Layering items with z-index
Grid items can occupy the same cell. If we return to our example with items positioned by line number, we can change this to make two items overlap.
<div class="wrapper"> <div class="box box1">One</div> <div class="box box2">Two</div> <div class="box box3">Three</div> <div class="box box4">Four</div> <div class="box box5">Five</div> </div>
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
grid-auto-rows: 100px;
}
.box1 {
grid-column-start: 1;
grid-column-end: 4;
grid-row-start: 1;
grid-row-end: 3;
}
.box2 {
grid-column-start: 1;
grid-row-start: 2;
grid-row-end: 4;
}
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.box {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
The item box2 is now overlapping box1, it displays on top as it comes later in the source order.
Controlling the order
We can control the order in which items stack up by using the z-index property - just as with positioned items. If we give box2 a lower z-index than box1 it will display below box1 in the stack.
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
grid-auto-rows: 100px;
}
.box1 {
grid-column-start: 1;
grid-column-end: 4;
grid-row-start: 1;
grid-row-end: 3;
z-index: 2;
}
.box2 {
grid-column-start: 1;
grid-row-start: 2;
grid-row-end: 4;
z-index: 1;
}
<div class="wrapper">
<div class="box box1">One</div>
<div class="box box2">Two</div>
<div class="box box3">Three</div>
<div class="box box4">Four</div>
<div class="box box5">Five</div>
</div>
* {box-sizing: border-box;}
.wrapper {
border: 2px solid #f76707;
border-radius: 5px;
background-color: #fff4e6;
}
.box {
border: 2px solid #ffa94d;
border-radius: 5px;
background-color: #ffd8a8;
padding: 1em;
color: #d9480f;
}
.nested {
border: 2px solid #ffec99;
border-radius: 5px;
background-color: #fff9db;
padding: 1em;
}
Next Steps
In this article we have had a very quick look through the Grid Layout Specification. Have a play with the code examples, and then move onto the next part of this guide where we will really start to dig into the detail of CSS Grid Layout.