The purpose of this blog post is to provide you with a quick introduction to
the new W3C CSS 3 Grid Layout standard. You can use CSS Grid Layout in Metro style applications written with JavaScript to lay out
the content of an HTML page. CSS Grid Layout provides you with all of
the benefits of using HTML tables for layout without requiring you to actually use any HTML table elements.
Doing Page Layouts without Tables
Back in
the 1990’s, if you wanted to create a fancy website, then you would use HTML tables for layout. For example, if you wanted to create a standard three-column page layout then you would create an HTML table with three columns like this:
<table height="100%">
<tr>
<td valign="top" width="300px" bgcolor="
red">
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column
</td>
<td valign="top" bgcolor="green">
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column
</td>
<td valign="top" width="300px" bgcolor="blue">
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column
</td>
</tr>
</table>
When
the table above gets rendered out to a browser, you end up with
the following three-column layout:
The width of
the left
and right columns is fixed –
the width of
the middle column expands or contracts depending on
the width of
the browser.
Sometime around
the year 2005, everyone decided that using tables for layout was a bad idea. Instead of using tables for layout — it was collectively decided by
the spirit of
the Web — you should use Cascading Style Sheets instead.
Why is using HTML tables for layout bad? Using tables for layout breaks
the semantics of
the TABLE element. A TABLE element should be used only for displaying tabular information such as train schedules or moon phases. Using tables for layout is bad for accessibility (The Web Content Accessibility Guidelines 1.0 is explicit about this)
and using tables for layout is bad for separating content from layout (see http://CSSZenGarden.com).
Post 2005, anyone who used HTML tables for layout were encouraged to hold their heads down in shame.
That’s all well
and good, but
the problem with using CSS for layout is that it can be more difficult to work with CSS than HTML tables. For example, to achieve a standard three-column layout, you either need to use absolute positioning or floats. Here’s a three-column layout with floats:
<style type="text/css">
#container {
min-width: 800px;
}
#leftColumn {
float: left;
width: 300px;
height: 100%;
background-color:red;
}
#middleColumn {
background-color:green;
height: 100%;
}
#rightColumn {
float: right;
width: 300px;
height: 100%;
background-color:blue;
}
</style>
<div id="container">
<div id="rightColumn">
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column
</div>
<div id="leftColumn">
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column
</div>
<div id="middleColumn">
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column
</div>
</div>
The page above contains four DIV elements: a container DIV which contains a leftColumn, middleColumn,
and rightColumn DIV.
The leftColumn DIV element is floated to
the left
and the rightColumn DIV element is floated to
the right. Notice that
the rightColumn DIV appears in
the page before
the middleColumn DIV – this unintuitive ordering is necessary to get
the floats to work correctly (see http://stackoverflow.com/questions/533607/css-three-column-layout-problem).
The page above (almost) works with
the most recent versions of most browsers. For example, you get
the correct three-column layout in both Firefox
and Chrome:
And the layout mostly works with Internet Explorer 9 except for
the fact that for some strange reason
the min-width doesn’t work so when you shrink
the width of your browser, you can get
the following unwanted layout:
Notice how
the middle column (the green column) bleeds to
the left
and right.
People have solved these issues with more complicated CSS. For example, see:
http://matthewjamestaylor.com/blog/holy-grail-no-quirks-mode.htm
But, at this point, no one could argue that using CSS is easier or more intuitive than tables. It takes work to get a layout with CSS
and we know that we could achieve
the same layout more easily using HTML tables.
Using CSS Grid Layout
CSS Grid Layout is a new W3C standard which provides you with all of
the benefits of using HTML tables for layout without
the disadvantage of using an HTML TABLE element. In other words, CSS Grid Layout enables you to perform table layouts using pure Cascading Style Sheets.
The CSS Grid Layout standard is still in a “Working Draft” state (it is not finalized)
and it is located here:
http://www.w3.org/TR/css3-grid-layout/
The CSS Grid Layout standard is only supported by Internet Explorer 10
and there are no signs that any browser other than Internet Explorer will support this standard in
the near future. This means that it is only practical to take advantage of CSS Grid Layout when building Metro style applications with JavaScript.
Here’s how you can create a standard three-column layout using a CSS Grid Layout:
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
html, body, #container {
height: 100%;
padding: 0px;
margin: 0px;
}
#container {
display: -ms-grid;
-ms-grid-columns: 300px auto 300px;
-ms-grid-rows: 100%;
}
#leftColumn {
-ms-grid-column: 1;
background-color:red;
}
#middleColumn {
-ms-grid-column: 2;
background-color:green;
}
#rightColumn {
-ms-grid-column: 3;
background-color:blue;
}
</style>
</head>
<body>
<div id="container">
<div id="leftColumn">
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column
</div>
<div id="middleColumn">
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column
</div>
<div id="rightColumn">
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column
</div>
</div>
</body>
</html>
When
the page above is rendered in Internet Explorer 10, you get a standard three-column layout:
The page above contains four DIV elements: a container DIV which contains a leftColumn DIV, middleColumn DIV,
and rightColumn DIV.
The container DIV is set to Grid display mode with
the following CSS rule:
#container {
display: -ms-grid;
-ms-grid-columns: 300px auto 300px;
-ms-grid-rows: 100%;
}
The display property is set to
the value “-ms-grid”. This property causes
the container DIV to lay out its child elements in a grid.
(Notice that you use “-ms-grid” instead of “grid”.
The “-ms-“ prefix is used because
the CSS Grid Layout standard is still preliminary. This implementation only works with IE10
and it might change before
the final release.)
The grid columns
and rows are defined with
the “-ms-grid-columns”
and “-ms-grid-rows” properties.
The style rule above creates a grid with three columns
and one row.
The left
and right columns are fixed sized at 300 pixels.
The middle column sizes automatically depending on
the remaining space available.
The leftColumn, middleColumn,
and rightColumn DIVs are positioned within
the container grid element with
the following CSS rules:
#leftColumn {
-ms-grid-column: 1;
background-color:red;
}
#middleColumn {
-ms-grid-column: 2;
background-color:green;
}
#rightColumn {
-ms-grid-column: 3;
background-color:blue;
}
The “-ms-grid-column” property is used to specify
the column associated with
the element selected by
the style sheet selector.
The leftColumn DIV is positioned in
the first grid column,
the middleColumn DIV is positioned in
the second grid column,
and the rightColumn DIV is positioned in
the third grid column.
I find using CSS Grid Layout to be just as intuitive as using an HTML table for layout. You define your columns
and rows
and then you position different elements within these columns
and rows. Very straightforward.
Creating Multiple Columns
and Rows
In
the previous section, we created a super simple three-column layout. This layout contained only a single row. In this section, let’s create a slightly more complicated layout which contains more than one row:
The following page contains a header row, a content row,
and a footer row.
The content row contains three columns:
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
html, body, #container {
height: 100%;
padding: 0px;
margin: 0px;
}
#container {
display: -ms-grid;
-ms-grid-columns: 300px auto 300px;
-ms-grid-rows: 100px 1fr 100px;
}
#header {
-ms-grid-column: 1;
-ms-grid-column-span: 3;
-ms-grid-row: 1;
background-color: yellow;
}
#leftColumn {
-ms-grid-column: 1;
-ms-grid-row: 2;
background-color:red;
}
#middleColumn {
-ms-grid-column: 2;
-ms-grid-row: 2;
background-color:green;
}
#rightColumn {
-ms-grid-column: 3;
-ms-grid-row: 2;
background-color:blue;
}
#footer {
-ms-grid-column: 1;
-ms-grid-column-span: 3;
-ms-grid-row: 3;
background-color: orange;
}
</style>
</head>
<body>
<div id="container">
<div id="header">
Header, Header, Header
</div>
<div id="leftColumn">
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column,
Left Column, Left Column, Left Column
</div>
<div id="middleColumn">
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column,
Middle Column, Middle Column, Middle Column
</div>
<div id="rightColumn">
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column,
Right Column, Right Column, Right Column
</div>
<div id="footer">
Footer, Footer, Footer
</div>
</div>
</body>
</html>
In
the page above,
the grid layout is created with
the following rule which creates a grid with three rows
and three columns:
#container {
display: -ms-grid;
-ms-grid-columns: 300px auto 300px;
-ms-grid-rows: 100px 1fr 100px;
}
The header is created with
the following rule:
#header {
-ms-grid-column: 1;
-ms-grid-column-span: 3;
-ms-grid-row: 1;
background-color: yellow;
}
The header is positioned in column 1
and row 1. Furthermore, notice that
the “-ms-grid-column-span” property is used to span
the header across three columns.
CSS Grid Layout
and Fractional Units
When you use CSS Grid Layout, you can take advantage of fractional units. Fractional units provide you with an easy way of dividing up remaining space in a page.
Imagine, for example, that you want to create a three-column page layout. You want
the size of
the first column to be fixed at 200 pixels
and you want to divide
the remaining space among
the remaining three columns.
The width of
the second column is equal to
the combined width of
the third
and fourth columns.
The following CSS rule creates four columns with
the desired widths:
#container {
display: -ms-grid;
-ms-grid-columns: 200px 2fr 1fr 1fr;
-ms-grid-rows: 1fr;
}
The fr unit represents a fraction.
The grid above contains four columns.
The second column is two times
the size (2fr) of
the third (1fr)
and fourth (1fr) columns. When you use
the fractional unit,
the remaining space is divided up using fractional amounts.
Notice that
the single row is set to a height of 1fr.
The single grid row gobbles up
the entire vertical space.
Here’s
the entire HTML page:
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
html, body, #container {
height: 100%;
padding: 0px;
margin: 0px;
}
#container {
display: -ms-grid;
-ms-grid-columns: 200px 2fr 1fr 1fr;
-ms-grid-rows: 1fr;
}
#firstColumn {
-ms-grid-column: 1;
background-color:red;
}
#secondColumn {
-ms-grid-column: 2;
background-color:green;
}
#thirdColumn {
-ms-grid-column: 3;
background-color:blue;
}
#fourthColumn {
-ms-grid-column: 4;
background-color:orange;
}
</style>
</head>
<body>
<div id="container">
<div id="firstColumn">
First Column, First Column, First Column
</div>
<div id="secondColumn">
Second Column, Second Column, Second Column
</div>
<div id="thirdColumn">
Third Column, Third Column, Third Column
</div>
<div id="fourthColumn">
Fourth Column, Fourth Column, Fourth Column
</div>
</div>
</body>
</html>
Summary
There is more in
the CSS 3 Grid Layout standard than discussed in this blog post. My goal was to describe
the basics. If you want to learn more than you can read through
the entire standard at http://www.w3.org/TR/css3-grid-layout/
In this blog post, I described some of
the difficulties that you might encounter when attempting to replace HTML tables with Cascading Style Sheets when laying out a web page. I explained how you can take advantage of
the CSS 3 Grid Layout standard to avoid these problems when building Metro style applications using JavaScript. CSS 3 Grid Layout provides you with all of
the benefits of using HTML tables for laying out a page without requiring you to use HTML table elements.
