diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 60b0bb96..928c7a55 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -24,7 +24,7 @@ jobs:
           yarn install --immutable
           yarn build
       - name: Upload built files
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: built
           path: .svelte-kit
@@ -40,7 +40,7 @@ jobs:
           node-version-file: .nvmrc
           cache: yarn
       - name: Download built files
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: built
           path: .svelte-kit
@@ -60,7 +60,7 @@ jobs:
           node-version-file: .nvmrc
           cache: yarn
       - name: Download built files
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: built
           path: .svelte-kit
diff --git a/src/lib/components/colors/FormatGroup.svelte b/src/lib/components/colors/FormatGroup.svelte
new file mode 100644
index 00000000..28fb4c82
--- /dev/null
+++ b/src/lib/components/colors/FormatGroup.svelte
@@ -0,0 +1,57 @@
+<script lang="ts">
+  import { inGamut } from 'colorjs.io/fn';
+  import type { PlainColorObject } from 'colorjs.io/types/src/color';
+
+  import Output from '$lib/components/colors/Output.svelte';
+  import type { FormatGroup } from '$lib/constants';
+  import { ColorSpace } from '$lib/stores';
+  import { getSpaceFromFormatId } from '$lib/utils';
+
+  import ExternalLink from '../util/ExternalLink.svelte';
+
+  export let type: 'bg' | 'fg';
+  export let color: PlainColorObject;
+  export let formatGroup: FormatGroup;
+
+  function inGamutForSpace(color: PlainColorObject) {
+    if (!formatGroup.gamutFormat) return true;
+    const gamutSpace = ColorSpace.get(
+      getSpaceFromFormatId(formatGroup.gamutFormat),
+    );
+    return inGamut(color, gamutSpace);
+  }
+  $: isInGamut = inGamutForSpace(color);
+</script>
+
+<div data-content="format-group">
+  <div class="format-group-heading">
+    <h2 class="label section-heading">{formatGroup.name}</h2>
+    {#if !isInGamut}
+      <span data-color-info="warning"
+        >Selected color is <ExternalLink
+          href="https://www.w3.org/TR/css-color-4/#out-of-gamut"
+          >outside the {formatGroup.gamutName} gamut.</ExternalLink
+        ></span
+      >
+    {/if}
+  </div>
+  {#each formatGroup.formats as format (format)}
+    <Output {type} {color} {format} />
+  {/each}
+</div>
+
+<style lang="scss">
+  [data-content~='format-group'] {
+    --heading-transform: none;
+
+    margin-block-end: var(--double-gutter);
+  }
+
+  .format-group-heading {
+    align-items: baseline;
+    display: flex;
+    flex-wrap: wrap;
+    gap: var(--shim);
+    margin-block-end: var(--gutter);
+  }
+</style>
diff --git a/src/lib/components/colors/Formats.svelte b/src/lib/components/colors/Formats.svelte
index ef706db6..a19ab637 100644
--- a/src/lib/components/colors/Formats.svelte
+++ b/src/lib/components/colors/Formats.svelte
@@ -1,31 +1,47 @@
 <script lang="ts">
   import type { PlainColorObject } from 'colorjs.io/types/src/color';
 
-  import Output from '$lib/components/colors/Output.svelte';
-  import type { ColorFormatId } from '$lib/constants';
-  import { FORMATS } from '$lib/constants';
+  import FormatGroup from '$lib/components/colors/FormatGroup.svelte';
+  import type {
+    ColorFormatId,
+    FormatGroup as FormatGroupType,
+  } from '$lib/constants';
+  import { FORMAT_GROUPS } from '$lib/constants';
 
   export let type: 'bg' | 'fg';
   export let color: PlainColorObject;
   export let format: ColorFormatId;
 
+  function otherFormatGroups(
+    selectedFormat: ColorFormatId,
+  ): typeof FORMAT_GROUPS {
+    const otherFormats: FormatGroupType[] = [];
+    FORMAT_GROUPS.forEach((group) => {
+      const groupFormats = group.formats.filter((s) => s !== selectedFormat);
+      if (groupFormats.length) {
+        otherFormats.push({ ...group, formats: groupFormats });
+      }
+    });
+    return otherFormats;
+  }
+
   $: displayType = type === 'bg' ? 'Background' : 'Foreground';
-  $: otherFormats = FORMATS.filter((s) => s !== format);
+  $: otherFormats = otherFormatGroups(format);
 </script>
 
 <div data-content="formats" data-column="tool">
-  <h4 class="small-only label">{displayType} Color</h4>
-  {#each otherFormats as format (format)}
-    <Output {type} {color} {format} />
+  <h2 class="small-only label">{displayType} Color</h2>
+  {#each otherFormats as formatGroup}
+    <FormatGroup {type} {color} {formatGroup} />
   {/each}
 </div>
 
 <style lang="scss">
   [data-content~='formats'] {
-    margin-bottom: var(--double-gutter);
+    margin-block-end: var(--double-gutter);
   }
 
-  .label {
-    --label-margin-bottom: var(--gutter);
+  .small-only {
+    --label-margin-block-end: var(--gutter);
   }
 </style>
diff --git a/src/lib/components/colors/Header.svelte b/src/lib/components/colors/Header.svelte
index 3d96363f..407c2fd3 100644
--- a/src/lib/components/colors/Header.svelte
+++ b/src/lib/components/colors/Header.svelte
@@ -165,7 +165,7 @@
   }
 
   [data-label] {
-    --label-margin-bottom: var(--half-shim);
+    --label-margin-block-end: var(--half-shim);
     grid-area: label;
   }
 
diff --git a/src/lib/components/colors/Output.svelte b/src/lib/components/colors/Output.svelte
index 6a906f44..37a7db09 100644
--- a/src/lib/components/colors/Output.svelte
+++ b/src/lib/components/colors/Output.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { inGamut, serialize, to } from 'colorjs.io/fn';
+  import { serialize, to } from 'colorjs.io/fn';
   import type { PlainColorObject } from 'colorjs.io/types/src/color';
 
   import SupportWarning from '$lib/components/colors/SupportWarning.svelte';
@@ -13,7 +13,6 @@
 
   $: targetSpace = getSpaceFromFormatId(format);
   $: targetColor = to(color, targetSpace);
-  $: isInGamut = inGamut(targetColor);
   $: targetColorValue = serialize(targetColor, {
     format,
     inGamut: false,
@@ -21,32 +20,21 @@
 </script>
 
 <ul data-group="output {type}">
-  <li>
+  <li data-testid={`format-${format}`}>
     <CopyButton text={targetColorValue} />
     <span data-color-info="value">{targetColorValue}</span>
     <SupportWarning {format} />
-    {#if !isInGamut}
-      <span data-color-info="warning"
-        >This color is outside the {targetColor.space.name} gamut.</span
-      >
-    {/if}
   </li>
 </ul>
 
 <style lang="scss">
+  [data-group~='output'] {
+    grid-column: 1 / -1;
+  }
+
   li {
     column-gap: 1ch;
     display: grid;
-    grid-template:
-      'copy color' auto
-      'copy message' 3ex / auto 1fr;
-  }
-
-  [data-color-info='value'] {
-    grid-area: color;
-  }
-
-  [data-color-info='warning'] {
-    grid-area: message;
+    grid-template-columns: auto 1fr;
   }
 </style>
diff --git a/src/lib/components/colors/Sliders.svelte b/src/lib/components/colors/Sliders.svelte
index 2e1e98d5..9afa1d5c 100644
--- a/src/lib/components/colors/Sliders.svelte
+++ b/src/lib/components/colors/Sliders.svelte
@@ -103,7 +103,7 @@
   }
 
   [data-group~='sliders'] {
-    --label-margin-bottom: var(--half-shim);
+    --label-margin-block-end: var(--half-shim);
     margin-bottom: var(--triple-gutter);
   }
 
diff --git a/src/lib/components/colors/index.svelte b/src/lib/components/colors/index.svelte
index e666ed02..ee82c135 100644
--- a/src/lib/components/colors/index.svelte
+++ b/src/lib/components/colors/index.svelte
@@ -18,7 +18,6 @@
   <Sliders type="fg" color={fg} format={$format} />
 </form>
 
-<h3 class="label section-heading">Additional Formats</h3>
 <div data-layout="split">
   <Formats type="bg" color={$bg} format={$format} />
   <Formats type="fg" color={$fg} format={$format} />
diff --git a/src/lib/components/ratio/index.svelte b/src/lib/components/ratio/index.svelte
index db8e1828..f0162277 100644
--- a/src/lib/components/ratio/index.svelte
+++ b/src/lib/components/ratio/index.svelte
@@ -38,7 +38,7 @@
   </div>
 
   <div class="contrast-defined">
-    <h4 class="label">AA Contrast Ratio</h4>
+    <h3 class="label">AA Contrast Ratio</h3>
 
     <dl>
       <dt><strong>{RATIOS.AA.Normal}</strong> : 1</dt>
@@ -48,7 +48,7 @@
       <dd>Large Text</dd>
     </dl>
 
-    <h4 class="label">AAA Contrast Ratio</h4>
+    <h3 class="label">AAA Contrast Ratio</h3>
     <dl>
       <dt><strong>{RATIOS.AAA.Normal}</strong> : 1</dt>
       <dd>Normal Text</dd>
@@ -57,7 +57,7 @@
       <dd>Large Text</dd>
     </dl>
 
-    <h4 class="label">Large Text Size</h4>
+    <h3 class="label">Large Text Size</h3>
     <dl>
       <dt><strong>≥ 24px</strong></dt>
       <dd>Regular Weight</dd>
@@ -141,8 +141,11 @@
     align-items: start;
     display: inline-flex;
     grid-area: number;
-    justify-content: flex-end;
     line-height: 0.7; // weird number alignment
+
+    @include config.between('sm-column-break', 'lg-page-break') {
+      justify-content: flex-end;
+    }
   }
 
   .result-ratio-number {
diff --git a/src/lib/constants.ts b/src/lib/constants.ts
index 885bf128..4bb8aea8 100644
--- a/src/lib/constants.ts
+++ b/src/lib/constants.ts
@@ -24,6 +24,29 @@ export const FORMATS: ColorFormatId[] = [
   'srgb',
 ];
 
+export type FormatGroup = {
+  name: string;
+  formats: ColorFormatId[];
+  gamutFormat?: ColorFormatId;
+  gamutName?: string;
+};
+
+export const FORMAT_GROUPS: FormatGroup[] = [
+  {
+    name: 'sRGB FORMATS',
+    formats: ['hex', 'hsl', 'srgb'],
+    gamutFormat: 'srgb',
+    gamutName: 'sRGB',
+  },
+  { name: 'UNBOUNDED SPACES', formats: ['lab', 'lch', 'oklab', 'oklch'] },
+  {
+    name: 'DISPLAY P3 SPACE',
+    formats: ['p3'],
+    gamutFormat: 'p3',
+    gamutName: 'P3',
+  },
+];
+
 export const RATIOS = {
   AA: {
     Normal: 4.5,
diff --git a/src/sass/initial/_type.scss b/src/sass/initial/_type.scss
index f3f42728..baab320a 100644
--- a/src/sass/initial/_type.scss
+++ b/src/sass/initial/_type.scss
@@ -22,8 +22,7 @@
 
 h1,
 h2,
-h3,
-h4 {
+h3 {
   font-weight: normal;
   margin: 0;
 }
@@ -42,15 +41,13 @@ h4 {
   display: block;
   font-size: var(--heading-size, var(--label-size));
   letter-spacing: var(--heading-letterspacing, 0.05rem);
-  margin-bottom: var(--label-margin-bottom, 0);
+  margin-block-end: var(--label-margin-block-end, 0);
   text-transform: var(--heading-transform, uppercase);
 }
 
 .section-heading {
   @include heading;
 
-  --label-margin-bottom: var(--gutter-plus);
-
   @include config.below('sm-page-break') {
     --heading-size: var(--medium);
   }
diff --git a/test/js/fixtures.ts b/test/js/fixtures.ts
index 4f46fb68..61d597f2 100644
--- a/test/js/fixtures.ts
+++ b/test/js/fixtures.ts
@@ -18,3 +18,9 @@ export const HSL_BLACK: PlainColorObject = {
 };
 
 export const HSL_WHITE_SERIALIZED = serialize(HSL_WHITE, { inGamut: false });
+
+export const OUT_OF_BOUNDED_GAMUTS: PlainColorObject = {
+  space: ColorSpace.get('oklch'),
+  coords: [1, 1, 1],
+  alpha: 1,
+};
diff --git a/test/js/lib/components/colors/FormatGroup.spec.ts b/test/js/lib/components/colors/FormatGroup.spec.ts
new file mode 100644
index 00000000..1c90f326
--- /dev/null
+++ b/test/js/lib/components/colors/FormatGroup.spec.ts
@@ -0,0 +1,36 @@
+import { render } from '@testing-library/svelte';
+
+import FormatGroup from '$lib/components/colors/FormatGroup.svelte';
+import { FORMAT_GROUPS } from '$src/lib/constants';
+import { HSL_WHITE, OUT_OF_BOUNDED_GAMUTS } from '$test/fixtures';
+
+describe('FormatGroup', () => {
+  it('renders selected group', () => {
+    const FORMAT_GROUP = FORMAT_GROUPS[0]!;
+    const { getByTestId, getByText } = render(FormatGroup, {
+      type: 'bg',
+      color: HSL_WHITE,
+      formatGroup: FORMAT_GROUP,
+    });
+
+    expect(getByText(FORMAT_GROUP.name)).toBeVisible();
+    FORMAT_GROUP.formats.forEach((format) => {
+      expect(getByTestId(`format-${format}`)).toBeVisible();
+    });
+  });
+
+  it('renders warning if out of gamut', () => {
+    const FORMAT_GROUP = FORMAT_GROUPS[0]!;
+    const { getByTestId, getByText } = render(FormatGroup, {
+      type: 'bg',
+      color: OUT_OF_BOUNDED_GAMUTS,
+      formatGroup: FORMAT_GROUP,
+    });
+
+    expect(getByText(FORMAT_GROUP.name)).toBeVisible();
+    FORMAT_GROUP.formats.forEach((format) => {
+      expect(getByTestId(`format-${format}`)).toBeVisible();
+    });
+    expect(getByText('outside the sRGB gamut.')).toBeVisible();
+  });
+});
diff --git a/test/js/lib/components/colors/Output.spec.ts b/test/js/lib/components/colors/Output.spec.ts
index 16f3e3bb..93882a10 100644
--- a/test/js/lib/components/colors/Output.spec.ts
+++ b/test/js/lib/components/colors/Output.spec.ts
@@ -1,9 +1,7 @@
 import { render } from '@testing-library/svelte';
 import { serialize, to } from 'colorjs.io/fn';
-import type { PlainColorObject } from 'colorjs.io/types/src/color';
 
 import Output from '$lib/components/colors/Output.svelte';
-import { ColorSpace } from '$lib/stores';
 import { HSL_WHITE, HSL_WHITE_SERIALIZED } from '$test/fixtures';
 
 describe('Output', () => {
@@ -28,19 +26,4 @@ describe('Output', () => {
       getByText(serialize(to(HSL_WHITE, 'oklch'), { inGamut: false })),
     ).toBeVisible();
   });
-
-  it('renders warning if out of gamut', () => {
-    const color: PlainColorObject = {
-      space: ColorSpace.get('oklch'),
-      coords: [0.01, 0.02, 0],
-      alpha: 1,
-    };
-    const { getByText } = render(Output, {
-      type: 'fg',
-      color,
-      format: 'hsl',
-    });
-
-    expect(getByText('outside the HSL gamut', { exact: false })).toBeVisible();
-  });
 });