Responsive web

Responsive web design (RWD) is an approach to web design that makes web pages render well on a variety of devices and window or screen sizes from minimum to maximum display size. Recent work also considers the viewer proximity as part of the viewing context as an extension for RWD.^[1] Content, design and performance are necessary across all devices to ensure usability and satisfaction  Responsive web design has become more important as the amount of mobile device user has come to account for more than half of total internet traffic.

In responsive design, page elements reshuffle as the viewport grows or shrinks. A three-column desktop design may reshuffle to two columns for a tablet and a single column for a smartphone. Responsive design relies on proportion-based grids to rearrange content and design elements.

Because responsive design relies on shuffling elements around the page, design and development need to work closely together to ensure a usable experience across devices. Responsive design often turns into solving a puzzle — how to reorganize elements on larger pages to fit skinnier, longer pages or vice versa. For a responsive design to be successful, the design must also be usable at all screen resolutions and sizes.

When elements move around the page, the user experience can be completely different from one view of the site to the next. It is important that design and development teams work together not to just determine how the content should be shuffled around, but to also see what the end result of that shift looks like and how it affects the user experience.

The Pattern Library uses the Bootstrap 4 grid system.

The grid system is composed of elements with row and col-* classes. All column elements should be placed inside the row element. For the columns to take up 100% of the row width, the column classes should add up to 12.

For more information see Bootstrap’s documentation on their grid system.
.col-4
.col-4
.col-4
.col-sm-4
.col-sm-4
.col-sm-4
.col-md-4
.col-md-4
.col-md-4
.col-lg-4
.col-lg-4
.col-lg-4
.col-xl-4
.col-xl-4
.col-xl-4

Three equal columns

Get three equal-width columns starting at desktops and scaling to large desktops. On mobile devices, tablets and below, the columns will automatically stack.
.col-md-4
.col-md-4
.col-md-4

Three unequal columns

Get three columns starting at desktops and scaling to large desktops of various widths. Remember, grid columns should add up to twelve for a single horizontal block. More than that, and columns start stacking no matter the viewport.
.col-md-3
.col-md-6

Two columns

Get two columns starting at desktops and scaling to large desktops.
.col-md-8
.col-md-4

Full width, single column

No grid classes are necessary for full-width elements.

Two columns with two nested columns

Per the documentation, nesting is easy—just put a row of columns within an existing column. This gives you two columns starting at desktops and scaling to large desktops, with another two (equal widths) within the larger column.

At mobile device sizes, tablets and down, these columns and their nested columns will stack.
.col-md-6
.col-md-6
.col-md-4

.col-md-8

Mixed: mobile and desktop

The Bootstrap v4 grid system has five tiers of column classes: all breakpoints (beginning at extra small breakpoints), sm (small), md (medium), lg (large), and xl (extra large). You can use nearly any combination of these classes to create more dynamic and flexible layouts.

Each tier of classes scales up, meaning if you plan on setting the same widths for md, lg, and xl breakpoints, you only need to specify the md column class.
.col-12 .col-md-8
.col-6 .col-md-4
.col-6 .col-md-4
.col-6 .col-md-4
.col-6 .col-md-4
.col-6
.col-6

Mixed: mobile, tablet, and desktop

.col-12 .col-sm-6 .col-lg-8
.col-6 .col-lg-4
.col-6 .col-sm-4
.col-6 .col-sm-4
.col-6 .col-sm-4

Offset, push, and pull resets

Reset offsets, pushes, and pulls at specific breakpoints.
.col-sm-5 .col-md-6
.col-sm-5 .offset-sm-2 .col-md-6 .offset-md-0
.col-sm-6 .col-md-5 .col-lg-6
.col-sm-6 .col-md-5 .offset-md-2 .col-lg-6 .offset-lg-0