Grids are a powerfull feature of CSS but they can be a little overwhelming at first. There are rows, columns, areas, lines, and multiple syntaxes for defining layouts. How do these concepts fit together and how to use them effectively?
In this article, we'll go through some basic concepts of CSS grids and learn how we can use grids to build layouts. My goal is to shed some light on how to define grid areas grid lines, which I found somewhat confusing when learning CSS grids.
Basics and terminology
A CSS grid is a display type that sets the layout of its children according to the grid specification.
Grids are built of columns, rows, areas, cells, lines, tracks, and gutters. To understand how these relate to each other, let's go through some definitions. So, bear with me 🐻
Columns are vertical tracks and contain the space between two vertical grid lines
Rows then are horizontal tracks and contain the space between two horizontal grid lines
What are tracks and grid lines then? Well, tracks and lines are how we specify our grid. A track is a space between two parallel lines and lines are created when we define the tracks for our grid. Tracks can be defined using grid-template-columns, grid-template-rows, and grid-template-areas CSS rules.
The smallest element in a CSS grid is a cell. It's an area defined by grid lines in all directions with no lines running through it.
Gutters are spacing between tracks and are defined using column-gap, row-gap, and gap CSS rules.
The grid in the example above is defined with the following CSS declarations
grid-template-columns: [first-col-start] 1fr [first-col-end second-col-start] 1fr [second-col-end third-col-start] 1fr [third-col-end];
grid-template-rows: [first-row-start] 1fr [first-row-end second-row-start] 1fr [second-row-end third-row-start] 1fr [third-row-end];
grid-template-columns property defines our grid columns. The syntax for grid-template-colums has multiple ways to define the columns. In it's simplest form, grid-template-colums takes a list of sizes to use as column widths. For example, grid-template-colums: 1fr 1fr 1fr would create a grid with 3 columns of equal width. fr is a special grid unit that means a fraction.
In our example, we are using a grid-template-columns syntax which has named grid lines using the bracket [line-name] syntax. Notice that some of the lines we've defined have two names, such as [first-col-end second-col-start]. Giving two names will make it easier to define our grid areas later on because of a special feature of CSS grids called implicit grid areas.
Implicit grid areas
While you can name your grid lines with any name, I've chosen to end them with start or end. This may seem like a minor detail, but it unlocks 🔓 a "hidden" feature. Grid area names will now be created for us. So using grid line names first-col-start and first-col-end on adjacent lines will create a grid area named first-col 🥳 We can now use first-col when we are defining grid areas with grid-column or grid-area properties.
Side panel layout with named grid lines
Next, let's take a look at a layout example with a navigation header, content area, sider panel, and a footer. We will define our grid lines by name and using those names when we define the areas of the different layout components.
The thing to note is that the browser will automatically create grid areas for us when we define grid lines. Vice versa, if we define our grid using grid-template-areas, we will automatically get named grid lines generated for us.
To get started, here's the HTML structure we will be working with.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>Side panel layout</title>
</head>
<body>
<nav>nav</nav>
<main>
main
</main>
<aside>
side
</aside>
<footer>
footer
</footer>
</body>
</html>
We will set the html and body height to 100% with no padding or margin so the grid will have the full size of the page.
html {
height: 100%;
padding: 0;
}
body {
height: 100%;
padding: 0;
margin: 0;
}
Next, we'll add display: grid to the body and define our column grid lines using the grid-template-columns CSS rule. This declares two columns that are defined by four named grid lines: side-start, side-end, main-start, and main-end. The first column will be 200px wide, while the other column has a width of auto.
body {
/* ... */
display: grid;
grid-template-columns: [side-start] 200px [side-end main-start] auto [main-end];
grid-template-rows: [nav-start] 50px [nav-end content-start] auto [content-end footer-start] 80px [footer-end];
}
When we use grid-template-colums and grid-template-rows with grid line names like this, named columns and rows will be automatically generated for us 🥳. In this case, the grid we will get the columns start, side, and main and the rows nav, content, and footer.
If we didn't care about the column and row names, we could just write grid-template-columns: 200px auto and grid-template-rows: 50px auto 80px to define the same layout.
Next we will define how our HTML elements will fit into the columns and rows.
nav {
grid-row: nav;
grid-column: side / main;
}
Because we have the generated row and column names, declaring the nav-element position and size can be done with grid-row and grid-column declarations. We are setting grid-column to side / main which tells the browser to extend the nav element from the start of the side column to the end of the main column.
main {
grid-area: content / main;
}
Defining the position and size of the main-element can be done using a single grid-area declaration. grid-area is a shorthand for setting grid-row-start, grid-column-start, grid-row-end, and grid-column-end. Because we are setting only two values (content and main) this is the equivalent of setting the row and column ending to the same values as start.
main {
grid-row-start: content;
grid-row-end: content;
grid-column-start: main;
grid-column-end: main;
}
You could also use the grid lines to define these values.
main {
grid-row-start: content-start;
grid-row-end: content-end;
grid-column-start: main-start;
grid-column-end: main-end;
}
For the sidebar we will use grid-area and grid-row-end to define the area.
aside {
grid-area: content / side;
grid-row-end: footer;
}
The grid-area declaration is similar to the one we used before. With the grid-row-end declaration, we make the sidebar extend to the bottom of the screen to the end of the footer row. This is cool, because it shows how powerful CSS grids can be 😎
Lastly, we define the footer CSS.
footer {
grid-row: footer;
grid-column: main;
}
Here we're using the grid-row and grid-column declarations. This is the equivalent of writing grid-area: footer / main.
Now we have all the CSS we need for our layout 🥳 If you want to check out the full HTML/CSS code, you can check the out at codesandbox.io. There you'll also find two other layout examples made using CSS grids.
There's more to it
I hope this article has shed some light on creating layouts using CSS grids. There are, however many features we didn't cover. I've compiled here a few resources which you might find interesting if you want to dig deeper.
MDN on CSS Grid Layout
CSS-Tricks - A complete guide to grid
Build Modern Layouts using CSS Grid - Hiroko Nishimura
Build Complex Layouts with CSS Grid Layout - Rory Smith
Photo by Sharon McCutcheon on Unsplash
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