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CSS Layout in 2017
with
CSS Grid & Flexbox Rachel Andrew, Laracon Online
Rachel Andrew
rachelandrew.co.uk
@rachelandrew
CSS Working Group Invited Expert
Google Developer Expert for Web Technologies
Co-founder Perch CMS: https://grabaperch.com
Contact: [email protected]
Modern CSS Layout?
• Floats
• Inline-block
• display: table
• Absolute & Relative positioning
• Frameworks … lots of frameworks
Our great hopes for layout
• Flexboxhttps://drafts.csswg.org/css-flexbox/
• CSS Grid Layouthttps://drafts.csswg.org/css-grid/
• Box Alignmenthttps://drafts.csswg.org/css-align/
The new CSS for Layout
Items in our layouts understand themselves as part of a complete layout.
Flexbox
Full height columns with flexbox, taking advantage of default alignment values.
.wrapper { display: flex; } .sidebar { flex: 1 1 30%; } .content { flex: 1 1 70%; }
Grid Layout
Full height columns in CSS Grid Layout.
.wrapper { display: grid; grid-template-columns: 30% 70%; } .sidebar { grid-column: 1; } .content { grid-column: 2; }
Separation of source and display
Flexbox
The flex-direction property can take a value of row to display things as a row or column to display them as a column.
nav ul{ display: flex; justify-content: space-between; flex-direction: row; }
Flexbox
The visual order can be switched using row-reverse or column-reverse.
nav ul{ display: flex; justify-content: space-between; flex-direction: row-reverse; }
Flexbox
Adding display: flex to our container element causes the items to display flexibly in a row.
.wrapper { display: flex; }
Flexbox
The order property means we can change the order of flex items using CSS.
This does not change their source order.
li:nth-child(1) { order: 3; } li:nth-child(2) { order: 1; } li:nth-child(3) { order: 4; } li:nth-child(4) { order: 2; }
Grid Layout
I have created a grid on my wrapper element.
The grid has 3 equal width columns.
Rows will be created as required as we position items into them.
.wrapper { display: grid; grid-template-columns: 1fr 1fr 1fr; }
Grid Layout
I am positioning my elements using CSS Grid Layout line-based positioning.
Setting a column and a row line using the grid-column and grid-row properties.
li:nth-child(1) { grid-column: 3 ; grid-row: 2 ; }
li:nth-child(2) { grid-column: 1 ; grid-row: 2 ; }
li:nth-child(3) { grid-column: 1 ; grid-row: 1 ; } li:nth-child(4) { grid-column: 2 ; grid-row: 1 ; }
CSS Grid automatic placement
http://www.w3.org/TR/2015/WD-css-grid-1-20150917/#grid-auto-flow-property
https://rachelandrew.co.uk/archives/2015/04/14/grid-layout-automatic-placement-and-packing-modes/
Grid Layout
When using automatic placement we can create rules for items in our document - for example displaying portrait and landscape images differently.
.wrapper { display: grid; grid-template-columns: 1fr 1fr 1fr 1fr; grid-template-rows: auto; }
.landscape { grid-column-end: span 2; }
grid-auto-flow
The default value of grid-auto-flow is sparse. Grid will move forward planning
items skipping cells if items do not fit .
Grid Layout
With a dense packing mode grid will move items out of source order to backfill spaces. .wrapper {
display: grid; grid-template-columns: 1fr 1fr 1fr 1fr; grid-template-rows: auto; grid-auto-flow: dense; }
.landscape { grid-column-end: span 2; }
grid-auto-flow
With grid-auto-flow dense items are displayed out of source order. Grid
backfills any suitable gaps.
With great power comes responsibility.
Power and responsibility
• Good = creating the most accessible source order and using Grid or Flexbox to get the optimal display for each device.
• Bad = using Grid or Flexbox as an excuse to forget about the source.
• Terrible - stripping out semantic elements to make everything a grid or flex item.
https://drafts.csswg.org/css-flexbox/#order-accessibility
Authors must use order only for visual, not logical, reordering of content. Style sheets that use order to perform logical reordering are non-conforming.
Léonie Watson | On CSS accessibility and drinking tea | CSS Day 2016
https://vimeo.com/180566024
Control of alignment
CSS Box Alignment Module Level 3
“This module contains the features of CSS relating to the alignment of boxes within their containers in the various CSS box layout models: block layout, table layout, flex layout, and grid layout.” - https://drafts.csswg.org/css-align/
It’s 2017. We can now centre things.
Box Alignment Properties
justify-content
align-content
justify-self
align-self
justify-items
align-items
Flexbox
The justify-content property is set to space-between.
The items at each end are placed against the container and the remaining space distributed evenly.
nav ul{ display: flex; justify-content: space-between; flex-direction: row; }
Grid
If there is space in the grid container after all column and row tracks have been added.
Use space-around and space-between to space the tracks.
.wrapper { width: 500px; height: 400px; display: grid; grid-gap: 10px; grid-template-columns: repeat(4, 80px); grid-template-rows: repeat(3,100px); align-content: space-around; justify-content: space-between; }
I can create this same layout with flexbox or Grid.
With flexbox the items are laid out in a row.
.wrapper { display: flex; }
.wrapper li { flex: 1 0 25%; }
The first item is at the default stretch and as the tallest item is dictating the height of the flex container.
The second is entered in the container.
The third aligned to the start.
The fourth aligned to the end.
.wrapper li:nth-child(2) { align-self: center; }
.wrapper li:nth-child(3) { align-self: flex-start; }
.wrapper li:nth-child(4) { align-self: flex-end; }
For Grid I use a single row, 4 column Grid.
.wrapper { display: grid; grid-template-columns: 1fr 1fr 1fr 1fr; }
Grid alignment properties for the three landscape images.
.wrapper li:nth-child(2) { align-self: center; }
.wrapper li:nth-child(3) { align-self: start; }
.wrapper li:nth-child(4) { align-self: end; }
https://rachelandrew.co.uk/css/cheatsheets/box-alignment
Responsive by default
Ethan Marcotte, Fluid Grids
“… every aspect of the grid—and the elements laid upon it—can be expressed as a proportion relative to its container.”
target ÷ context = result
h1 {
margin-left: 14.575%; /* 144px / 988px = 0.14575 */ width: 70.85%; /* 700px / 988px = 0.7085 */
}
Flexbox
The most simple flexbox example demonstrates the inherent flexibility.
The items will be displayed as a row, with equal space between each item.
nav ul{ display: flex; justify-content: space-between; }
The flex property
• flex-grow - add space
• flex-shrink - remove space
• flex-basis - the initial size before any growing or shrinking
Flexbox
flex: 1 1 300px;
flex-grow: 1
flex-shrink: 1;
flex-basis: 300px;
The initial width of our li is 300 pixels, however it can grow larger and shrink smaller than 300 pixels.
.wrapper { display: flex; } .wrapper li { flex: 1 1 300px; min-width: 1px; }
Flexbox
flex: 1 1 300px;
flex-grow: 1
flex-shrink: 1;
flex-basis: 300px;
If we allow the flex items to wrap we can see how flex-basis works by dragging the window smaller.
.wrapper { display: flex; flex-flow: row wrap; justify-content: space-around; } .wrapper li { flex: 1 1 300px; min-width: 1px; }
Flexbox
flex: 1 1 300px;
flex-grow: 1;
flex-shrink: 1;
flex-basis: 300px;
The 3rd item has
flex: 0 1 300px;
so cannot grow.
.wrapper { display: flex; } .wrapper li { flex: 1 1 300px; min-width: 1px; }
.wrapper li:nth-child(3) { flex: 0 1 300px; }
Flexbox
If we set the 3rd item to flex-grow: 2
This item will be assigned twice of much of the available free space after we have reached the 300 pixel initial width.
.wrapper { display: flex; } .wrapper li { flex: 1 1 300px; min-width: 1px; }
.wrapper li:nth-child(3) { flex: 2 1 300px; }
The CSS Grid Layout fr unit
Grid Layout
I am creating three grid column tracks, all 1fr in width.
This gives me three equally sized column tracks.
.wrapper { display: grid; grid-template-columns: 1fr 1fr 1fr; }
Grid Layout
If I create the first column as 600 pixels and then have two 1fr columns the 600 pixel track is removed from the available space and the remainder is distributed equally between the two columns.
.wrapper { display: grid; grid-template-columns: 600px 1fr 1fr; }
Grid Layout
With a 600 pixel column, a 1fr and a 3fr column. The 600 pixels is removed from the available space then the remaining space is divided by 4.
The 1fr column gets 25% and the 3fr column 75%.
.wrapper { display: grid; grid-template-columns: 600px 1fr 3fr; }
Flexbox for 1 dimensional layout.
CSS Grid is for 2 dimensional layout.
The value of the grid-template-columns property says:
repeat this track listing, auto-filing as many columns with a minimum width of 300 pixels and a maximum of 1fr.
.wrapper { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); }
Bringing it all together
Using the minmax() function with grid-auto-rows.
.home-hero { display: grid; grid-gap: 1px; grid-auto-rows: minmax(150px, auto); }
An item on the grid can become a grid or flex container itself.
In this case I am using flexbox and auto margins to push my content to the bottom of the box.
.special { display: flex; flex-direction: column; }
.special h3{ margin-top: auto; }
• Grid shipped in Firefox yesterday
• Grid is scheduled for Chrome 57 - next week
• Grid is in the current Safari Beta - probably shipping March/April.
IE and Edge still use their early implementation of CSS Grid Layout.
Feature Queries - your new best friend
Feature Queries
Test for support of property: value pairs.
@supports (display: grid) { .has-grid { /* CSS for grid browsers here */
} }
This example sets three elements to display: none
Using @supports I test to see if they have support and set display: block s they will become visible.
.has-flex,
.has-grid,
.has-grid-shapes { display: none; }
@supports (display: flex) { .has-flex { display: block; background-color: #0084AD; color: #fff; } }
@supports (display: grid) { .has-grid { display: block; background-color: #284C6D; color: #fff; } }
@supports ((display: grid) and (shape-outside: circle())) { .has-grid-shapes { display: block; background-color: #666; color: #fff; } }
Using Feature Queries
• Write CSS for browsers without support
• Override those properties inside the feature queries
• https://hacks.mozilla.org/2016/08/using-feature-queries-in-css/
• https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Grid_Layout/CSS_Grid_and_Progressive_Enhancement
Grid tips for Feature Queries
• Floated items that become grid or flex items lose their float behaviour
• vertical-align has no effect on a grid item
• Items set to display: inline-block or block become grid items
• Your overrides mostly change widths, margins and padding.
• If grid tracks or flex-basis seem to be using a size you didn’t expect, check your item widths!
Anything new in CSS you can use feature queries to detect support.
Thank you
Slides & Resources: https://rachelandrew.co.uk/speaking/event/laracon-online
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@rachelandrew | [email protected]
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https://rachelandrew.co.uk | https://grabaperch.com
