Add two sidecar layouts to layout component

.changeset/dry-elephants-provide.md

@@ -0,0 +1,6 @@
+---
+'@microsoft/atlas-site': minor
+'@microsoft/atlas-css': minor
+---
+
+Add sidecar-left and sidecar-right layouts and relevant documentation.

css/src/components/layout.scss

@@ -1,5 +1,9 @@
 @use 'sass:math';
 
+$quarter-widescreen: math.div($breakpoint-widescreen, 4);
+$half-widescreen: math.div($breakpoint-widescreen, 2);
+$three-quarters-widescreen: math.div($breakpoint-widescreen, 4) * 3;
+
 .layout {
 	display: flex;
 	flex-direction: column;
@@ -15,6 +19,14 @@
 	}
 }
 
+.layout-padding {
+	padding-inline: var(#{$layout-gap-custom-property-name}) !important;
+}
+
+.layout-margin {
+	margin-inline: var(#{$layout-gap-scalable-custom-property-name}) !important;
+}
+
 .layout-body {
 	display: grid;
 	width: 100%;
@@ -47,6 +59,16 @@
 	grid-area: footer;
 }
 
+.layout-body-hero,
+.layout-body-main,
+.layout-body-footer,
+.layout-body-aside,
+.layout-body-menu {
+	&:empty {
+		display: none;
+	}
+}
+
 .layout,
 .layout.layout-single {
 	.layout-body {
@@ -79,11 +101,8 @@
 				'footer footer footer';
 		}
 
-		$widescreen-side-columns-width: math.div($breakpoint-widescreen, 4);
-		$widescreen-main-width: math.div($breakpoint-widescreen, 2);
-
 		@include widescreen {
-			grid-template: auto auto 1fr auto / auto #{$widescreen-side-columns-width} #{$widescreen-main-width} #{$widescreen-side-columns-width} auto;
+			grid-template: auto auto 1fr auto / auto #{quarter-widescreen} #{$half-widescreen} #{quarter-widescreen} auto;
 			grid-template-areas:
 				'header header header header header'
 				'hero hero hero hero hero'
@@ -93,20 +112,78 @@
 	}
 }
 
-.layout-padding {
-	padding-inline: var(#{$layout-gap-custom-property-name}) !important;
-}
+.layout.layout-sidecar-left {
+	.layout-body-aside {
+		display: none;
+	}
 
-.layout-margin {
-	margin-inline: var(#{$layout-gap-scalable-custom-property-name}) !important;
+	.layout-body {
+		grid-template: auto auto auto 1fr auto / 1fr;
+		grid-template-areas: 'header' 'hero' 'menu' 'main' 'footer';
+
+		@include tablet {
+			grid-template: auto auto 1fr auto / 1fr 2fr;
+			grid-template-areas:
+				'header header'
+				'hero hero'
+				'menu main'
+				'footer footer';
+		}
+
+		@include desktop {
+			grid-template: auto auto 1fr auto / 1fr 3fr;
+			grid-template-areas:
+				'header header'
+				'hero hero'
+				'menu main'
+				'footer footer';
+		}
+
+		@include widescreen {
+			grid-template: auto auto 1fr auto / auto #{$quarter-widescreen} #{$three-quarters-widescreen} auto;
+			grid-template-areas:
+				'header header header header'
+				'hero hero hero hero'
+				'. menu main .'
+				'footer footer footer footer';
+		}
+	}
 }
 
-.layout-body-hero,
-.layout-body-main,
-.layout-body-footer,
-.layout-body-aside,
-.layout-body-menu {
-	&:empty {
+.layout.layout-sidecar-right {
+	.layout-body-menu {
 		display: none;
 	}
+
+	.layout-body {
+		grid-template: auto auto auto 1fr auto / 1fr;
+		grid-template-areas: 'header' 'hero' 'main' 'aside' 'footer';
+
+		@include tablet {
+			grid-template: auto auto 1fr auto / 2fr 1fr;
+			grid-template-areas:
+				'header header'
+				'hero hero'
+				'main aside '
+				'footer footer';
+		}
+
+		@include desktop {
+			grid-template: auto auto 1fr auto / 3fr 1fr;
+			grid-template-areas:
+				'header header'
+				'hero hero'
+				'main aside '
+				'footer footer';
+		}
+
+		@include widescreen {
+			grid-template: auto auto 1fr auto / auto #{$three-quarters-widescreen} #{$quarter-widescreen} auto;
+			grid-template-areas:
+				'header header header header'
+				'hero hero hero hero'
+				'. main aside .'
+				'footer footer footer footer';
+		}
+	}
 }

site/src/components/layout.md

@@ -19,6 +19,8 @@ This page is utilizing the holy grail layout, but you can use the buttons below
 <div class="buttons buttons-addons margin-top-sm display-inline-flex">
   <button class="button" data-set-layout="layout-holy-grail" aria-pressed="true">Holy grail</button>
   <button class="button" data-set-layout="layout-single">Single</button>
+  <button class="button" data-set-layout="layout-sidecar-left">Sidecar left</button>
+  <button class="button" data-set-layout="layout-sidecar-right">Sidecar right</button>
 </div>
 <button class="button margin-top-sm" data-toggle-debug aria-pressed="false">Toggle container labels</button>
 
@@ -68,14 +70,16 @@ There are two available layouts.
 
 - [`layout-single`](#layout-single)
 - [`layout-holy-grail`](#holy-grail-layout)
+- [`layout-sidecar-left`](#sidecar-left-layout)
+- [`layout-sidecar-right`](#sidecar-right-layout)
 
 ### Layout Single
 
 The `layout-single` class provides a simple stacked layout. It is equivalent to a series of marginless and paddingless stacked block level elements. All elements in a single layout should set their own margin somewhere within their nested containers. Most likely, you'll want to apply `.layout-margin` or some other container-like class to elements within the single layout. This is also the default layout that will render if no other class is provide.
 
 How do I apply it? `layout-single` to the `layout` element.
 
-Required elements: all, except `layout-body-hero`.
+Required elements: all except `layout-body-hero`.
 
 Allowed elements: all.
 
@@ -106,7 +110,7 @@ The specification for this layout is as follows.
 Named after a layout that [historically was difficult to implement](<https://en.wikipedia.org/wiki/Holy_grail_(web_design)>) the holy grail is stacked on narrow widths and progressively shows up to three columns as the screen widens.
 
 How do I apply it? `layout-holy-grail` to the `layout` element.
-Required elements: all, except `layout-body-hero`.
+Required elements: all except `layout-body-hero`.
 Allowed elements: all.
 
 The following block is arranged from narrow widths on the left to wider widths on the right.
@@ -136,6 +140,76 @@ The specification for this layout is as follows.
 | Desktop    | Menu, main, aside are side by side. Main is wider than menu.                                                                  |
 | Widescreen | Same as desktop with scaling gutter that keeps combined width of menu, main, aside to the width of the widescreen breakpoint. |
 
+### Sidecar left layout
+
+A "sidecar" is a smaller companion container that sits beside the main content container on tablet screens and wider. In `layout-sidecar-left` the sidecar refers to the `layout-body-menu` element, which sits to the left of `layout-body-main`. Unlike other layouts, this layout does not allow the usage of the `layout-body-aside` containers.
+
+How do I apply it? `layout-sidecar-left` to the `layout` element.
+Required elements: all except `layout-body-hero` and `layout-body-aside` (see allowed elements).
+Allowed elements: all except `layout-body-aside`.
+
+The following block is arranged from narrow widths on the left to wider widths on the right.
+
+```txt
+  ┌────────────┐   ┌──────────────┐ ┌──────────────────────┐
+  │ Header     │   │Header        │ │ Header               │
+  ├────────────┤   ├──────────────┤ ├──────────────────────┤
+  │ Hero       │   │Hero          │ │ Hero                 │
+  ├────────────┤   ├─────┬────────┤ ├──────┬───────────────┤
+  │ Menu       │   │Menu │ Main   │ │ Menu │ Main          │
+  ├────────────┤   │     │        │ │      │               │
+  │ Main       │   │     │        │ │      │               │
+  │            │   │     │        │ │      │               │
+  │            │   │     │        │ │      │               │
+  ├────────────┤   ├─────┴────────┤ ├──────┴───────────────┤
+  │ Footer     │   │Footer        │ │ Footer               │
+  └────────────┘   └──────────────┘ └──────────────────────┘
+```
+
+The specification for this layout is as follows.
+
+| Screensize       | Behavior                                                                                                                         |
+| ---------------- | -------------------------------------------------------------------------------------------------------------------------------- |
+| Narrow           | All elements are stacked.                                                                                                        |
+| Tablet - desktop | Menu and main are side by side. Main is wider than menu.                                                                         |
+| Widescreen       | Same as tablet-desktop with scaling gutter that keeps combined width of menu and main to the width of the widescreen breakpoint. |
+
+### Sidecar right layout
+
+The "sidecar" remains as defined in the section above, but in `layout-sidecar-left` the sidecar refers to the `layout-body-aside` element, which sits to the right of `layout-body-main` on tablet screens and wider. Unlike other layouts, this layout does not allow the usage of the `layout-body-menu` containers.
+
+How do I apply it? `layout-sidecar-right` to the `layout` element.
+Required elements: all except `layout-body-hero` and `layout-body-menu` (see allowed elements).
+Allowed elements: all except `layout-body-menu`.
+
+The following block is arranged from narrow widths on the left to wider widths on the right.
+
+```txt
+ ┌──────────────┐ ┌──────────────────────┐ ┌──────────────────────┐
+ │Header        │ │ Header               │ │ Header               │
+ ├──────────────┤ ├──────────────────────┤ ├──────────────────────┤
+ │Hero          │ │ Hero                 │ │ Hero                 │
+ ├────────┬─────┤ ├───────────────┬──────┤ ├───────────────┬──────┤
+ │Main    │Aside│ │ Main          │ Aside│ │ Main          │ Aside│
+ │        │     │ │               │      │ │               │      │
+ │        │     │ │               │      │ │               │      │
+ │        │     │ │               │      │ │               │      │
+ │        │     │ │               │      │ │               │      │
+ ├────────┴─────┤ ├───────────────┴──────┤ ├───────────────┴──────┤
+ │Footer        │ │ Footer               │ │ Footer               │
+ └──────────────┘ └──────────────────────┘ └──────────────────────┘
+```
+
+The specification for this layout is as follows.
+
+| Screensize       | Behavior                                                                                                                          |
+| ---------------- | --------------------------------------------------------------------------------------------------------------------------------- |
+| Narrow           | All elements are stacked.                                                                                                         |
+| Tablet - desktop | Main and aside are side by side. Main is wider than aside.                                                                        |
+| Widescreen       | Same as tablet-desktop with scaling gutter that keeps combined width of main and aside to the width of the widescreen breakpoint. |
+
+## Accessibility and ARIA landmarks
+
 ## Accessibility Concerns
 
 ### ARIA landmarks
@@ -161,7 +235,7 @@ Because layouts generally contain the same elements and because the current layo
 
 ```JavaScript
 document.documentElement.classList.remove('layout-single');
-document.documentElement.classList.remove('layout-holy-grail');
+document.documentElement.classList.add('layout-holy-grail');
 ```
 
 You'll seldom have occasion to do this in the middle of a user's visit, but it can be useful for things like opening a code editor in a wider layout or adopting a focused reading mode.

site/src/scaffold/index.scss

@@ -5,24 +5,11 @@
 @import './styles/overflow.scss';
 @import './styles/code-block.scss';
 @import './styles/burger.scss';
+@import './styles/layout-buttons.scss';
 
 // hack to mark markdown logo on '/' look a tad different, excludes header logo
 main img[src^='/atlas-light.'] {
 	width: 64px;
 	height: auto;
 	margin-bottom: 18px;
 }
-
-.layout-single {
-	[data-set-layout='layout-single'] {
-		@extend .button-primary;
-		@extend .button-filled;
-	}
-}
-
-.layout-holy-grail {
-	[data-set-layout='layout-holy-grail'] {
-		@extend .button-primary;
-		@extend .button-filled;
-	}
-}

site/src/scaffold/scripts/layout-page.ts

@@ -1,4 +1,9 @@
-const layoutsClasses = ['layout-single', 'layout-holy-grail'];
+const layoutsClasses = [
+	'layout-single',
+	'layout-holy-grail',
+	'layout-sidecar-left',
+	'layout-sidecar-right'
+];
 
 // A function that removes all classes that begin with layout- on the html element
 function setLayoutClass(layoutToSet: string) {

site/src/scaffold/styles/layout-buttons.scss

@@ -0,0 +1,6 @@
+$layouts: 'single', 'holy-grail', 'sidecar-left', 'sidecar-right';
+
+[data-set-layout][aria-pressed="true"] {
+	@extend .button-primary;
+	@extend .button-filled;
+}