diff --git a/resources/css/components/dialog.css b/resources/css/components/dialog.css
new file mode 100644
index 00000000..ff85919e
--- /dev/null
+++ b/resources/css/components/dialog.css
@@ -0,0 +1,58 @@
+/*
+ * `<x-modal>`'s dividers: the rule under the pinned header and the rule over the pinned actions.
+ *
+ * M3 lists a divider in the anatomy of both dialogs, 1dp high (docs/reference/m3/
+ * components-actions-communication-containment.md § Dialogs → Anatomy, Specs), in outline-variant
+ * (DividerTokens: Color = OutlineVariant, Thickness = 1dp, androidx Compose Material 3,
+ * Apache-2.0). A scrolling dialog keeps its title and buttons pinned and scrolls only what is
+ * between them (§ Dialogs → Behaviour), and a rule there only says something while content is
+ * hidden on its far side: the one under the header shows once the body is scrolled away from its
+ * top, the one over the actions while more of the body is below. resources/js/dialog.js marks the
+ * `<dialog>` with `data-overflow-top` and `data-overflow-bottom`; a row with `data-separator` (the
+ * `separator` prop) draws its rule whatever the scroll.
+ *
+ * Each rule is a pseudo-element laid over the edge of its own row's padding, as Material Web's
+ * dialog lays its dividers at the bottom of the headline and the top of the actions
+ * (material-components/material-web, dialog/internal/_dialog.scss): it takes no room, so showing
+ * it moves nothing, and it lies outside the body's scrollport, so no content scrolls over it. The
+ * rule is full-bleed, the width of the dialog. Only the head and actions of a dialog that has a
+ * body carry the hooks (resources/views/components/modal.blade.php).
+ *
+ * The child combinators tie a mark to its own dialog's rows, never to those of a dialog opened
+ * from inside its body. The rule fades on the effects-fast token, which reduced motion sets to
+ * zero (resources/css/tokens/motion.css), so there it simply appears.
+ */
+
+@layer components {
+    [data-dialog-head],
+    [data-dialog-actions] {
+        position: relative;
+    }
+
+    [data-dialog-head]::after,
+    [data-dialog-actions]::before {
+        content: '';
+        position: absolute;
+        inset-inline: 0;
+        height: 1px;
+        background-color: var(--md-sys-color-outline-variant);
+        opacity: 0;
+        pointer-events: none;
+        transition: opacity var(--md-sys-motion-effects-fast-duration) var(--md-sys-motion-effects-fast);
+    }
+
+    [data-dialog-head]::after {
+        bottom: 0;
+    }
+
+    [data-dialog-actions]::before {
+        top: 0;
+    }
+
+    dialog[data-overflow-top] > * > [data-dialog-head]::after,
+    dialog[data-overflow-bottom] > * > [data-dialog-actions]::before,
+    [data-dialog-head][data-separator]::after,
+    [data-dialog-actions][data-separator]::before {
+        opacity: 1;
+    }
+}
diff --git a/resources/css/material.css b/resources/css/material.css
index d6565b0e..e5fbcdd9 100644
--- a/resources/css/material.css
+++ b/resources/css/material.css
@@ -24,6 +24,7 @@
 @import './components/groups.css';
 @import './components/list.css';
 @import './components/collapse.css';
+@import './components/dialog.css';
 @import './components/field.css';
 @import './components/menu.css';
 @import './components/selection.css';
diff --git a/resources/js/dialog.js b/resources/js/dialog.js
new file mode 100644
index 00000000..a3b48a89
--- /dev/null
+++ b/resources/js/dialog.js
@@ -0,0 +1,50 @@
+/**
+ * `x-dialog-dividers`, on `<x-modal>`'s body — the one part of a dialog that scrolls: marks the
+ * `<dialog>` with `data-overflow-top` while the body is scrolled away from its top, and
+ * `data-overflow-bottom` while more of it is below. resources/css/components/dialog.css draws
+ * those as the dividers under the pinned header and over the pinned actions; a body that fits
+ * marks neither.
+ *
+ * The marks go on the `<dialog>` rather than the body because the dialog is `wire:ignore.self`: a
+ * Livewire morph hands the body back the server's attributes, which would wipe a mark until the
+ * next scroll, but it never touches the dialog's own.
+ *
+ * Measured on scroll, and whenever the body or what is in it changes size: the body when the window
+ * or the dialog does (opening, too — a closed dialog has no size, and the observer reports the
+ * one it opens to), and the element the component wraps around the slot when a morph, an image or
+ * a disclosure makes the content taller or shorter while the body stays at its cap.
+ */
+document.addEventListener('alpine:init', () => {
+    window.Alpine.directive('dialog-dividers', (el, _, { cleanup }) => {
+        const dialog = el.closest('dialog')
+
+        if (!dialog) {
+            return
+        }
+
+        // A pixel of slack: at a fractional device pixel ratio the end of a scroll can stop a
+        // fraction short of `scrollHeight`, which is rounded.
+        const measure = () => {
+            dialog.toggleAttribute('data-overflow-top', el.scrollTop >= 1)
+            dialog.toggleAttribute('data-overflow-bottom', el.scrollHeight - el.clientHeight - el.scrollTop >= 1)
+        }
+
+        const resizes = new ResizeObserver(measure)
+        resizes.observe(el)
+
+        const content = el.querySelector(':scope > [data-dialog-content]')
+
+        if (content) {
+            resizes.observe(content)
+        }
+
+        el.addEventListener('scroll', measure, { passive: true })
+
+        cleanup(() => {
+            resizes.disconnect()
+            el.removeEventListener('scroll', measure)
+            dialog.removeAttribute('data-overflow-top')
+            dialog.removeAttribute('data-overflow-bottom')
+        })
+    })
+})
diff --git a/resources/js/material.js b/resources/js/material.js
index 2b780e2a..f4ca5f2b 100644
--- a/resources/js/material.js
+++ b/resources/js/material.js
@@ -17,6 +17,7 @@ import './rich-tooltip.js'
 import './progress.js'
 import './list-rows.js'
 import './bottom-sheet.js'
+import './dialog.js'
 import './carousel.js'
 import './chips.js'
 import './field.js'
diff --git a/resources/views/components/modal.blade.php b/resources/views/components/modal.blade.php
index 6be807d1..ec150aad 100644
--- a/resources/views/components/modal.blade.php
+++ b/resources/views/components/modal.blade.php
@@ -28,7 +28,21 @@
      the buttons at the bottom" (docs/reference/m3/components-actions-communication-containment.md
      § Dialogs → Behaviour): the header and the action row are their own rows of the flex column
      and only the body between them scrolls, each with the 24dp padding the box used to carry.
-     `separator` draws M3's divider under the pinned header and above the pinned actions.
+
+     Between that body and the rows pinned around it go M3's optional dividers (the 1dp "Divider"
+     in both dialogs' anatomy, § Dialogs → Anatomy, Specs), each only while content is hidden on
+     its far side: the rule under the header once the body is scrolled away from its top, the rule
+     over the actions while more of the body is below, so a body that fits draws neither. On a
+     phone a full-screen dialog's top rule lies under its close-and-title bar, unless a subtitle
+     or an icon keeps the header there, and its action bar's rule follows the scroll like any
+     other. `separator` draws both rules whatever the scroll. The gaps M3 gives are split around
+     the rules — 8px above and 8px below the top one (16dp title to body), 8px above and 16px below
+     the bottom one (24dp body to actions) — so the scrolling body keeps room inside its edges for
+     a floating label or a focus ring, and a rule that appears moves nothing. Without a body there
+     is nothing to divide, and no rule. resources/css/components/dialog.css draws the rules;
+     `x-dialog-dividers` (resources/js/dialog.js), on the body, says which of them show, watching
+     the body and the one element wrapped around the slot, so content a Livewire render adds
+     counts.
 
      `alert` is M3's "on web, basic dialogs should have the alert dialog role": it sets
      `role="alertdialog"` and points `aria-describedby` at the body, for the dialog that
@@ -51,9 +65,12 @@
     $model = $attributes->wire('model')->value() ?: null;
     $id = $attributes->get('id') ?? 'material-dialog-'.substr(md5($model.'|'.$title), 0, 10);
     $header = filled($title) || filled($subtitle) || $icon;
+    $body = $slot->isNotEmpty();
+    // On a phone a full-screen dialog's bar names it, and the header hides unless an icon or a subtitle keeps it.
+    $barAboveBody = $fullscreen && (! $header || (! $icon && blank($subtitle)));
     $describedBy = implode(' ', array_filter([
         filled($subtitle) ? $id.'-subtitle' : null,
-        $alert && $slot->isNotEmpty() ? $id.'-body' : null,
+        $alert && $body ? $id.'-body' : null,
     ]));
 @endphp
 
@@ -89,7 +106,10 @@
         $boxClass,
     ])>
         @if ($fullscreen)
-            <div class="flex h-14 shrink-0 items-center gap-1 px-1 medium:hidden">
+            <div
+                @if ($body && $barAboveBody) data-dialog-head @if ($separator) data-separator @endif @endif
+                class="flex h-14 shrink-0 items-center gap-1 px-1 medium:hidden"
+            >
                 <x-livewire-material::button icon="close" :tooltip="__('Close')" x-on:click="close()" />
 
                 @if (filled($title))
@@ -100,7 +120,10 @@
 
         @if ($header)
             {{-- A full-screen dialog's bar names it on a phone, so only the subtitle stays there. --}}
-            <div @class(['shrink-0 px-6 pt-6', 'max-medium:hidden' => $fullscreen && ! $icon && blank($subtitle), 'text-center' => $icon])>
+            <div
+                @if ($body) data-dialog-head @if ($separator) data-separator @endif @endif
+                @class(['shrink-0 px-6 pt-6', 'pb-2' => $body, 'max-medium:hidden' => $fullscreen && ! $icon && blank($subtitle), 'text-center' => $icon])
+            >
                 @if ($icon)
                     <x-livewire-material::icon :name="$icon" class="mx-auto mb-4 size-6 text-secondary" />
                 @endif
@@ -112,33 +135,32 @@
                 @if (filled($subtitle))
                     <p id="{{ $id }}-subtitle" @class(['type-body-md text-on-surface-variant', 'mt-4' => filled($title) || $icon, 'max-medium:mt-0' => $fullscreen && ! $icon])>{{ $subtitle }}</p>
                 @endif
-
-                @if ($separator)
-                    <x-livewire-material::divider class="mt-4" />
-                @endif
             </div>
         @endif
 
-        @if ($slot->isNotEmpty())
-            <div id="{{ $id }}-body" @class([
+        @if ($body)
+            <div id="{{ $id }}-body" x-dialog-dividers @class([
                 'min-h-0 flex-1 overflow-y-auto px-6 type-body-md text-on-surface-variant',
-                'pt-4' => $header,
+                'pt-2' => $header,
+                'max-medium:pt-4' => $header && $barAboveBody,
                 'pt-6' => ! $header,
+                'pb-2' => isset($actions),
                 'pb-6' => ! isset($actions),
             ])>
-                {{ $slot }}
+                <div data-dialog-content>{{ $slot }}</div>
             </div>
         @endif
 
         @isset($actions)
-            @if ($separator)
-                <x-livewire-material::divider class="shrink-0" />
-            @endif
-
-            <div @class([
-                'flex shrink-0 flex-wrap items-center justify-end gap-2 px-6 pt-6 pb-6',
-                'max-medium:min-h-14 max-medium:border-t max-medium:border-outline-variant max-medium:pt-2 max-medium:pb-2' => $fullscreen,
-            ])>
+            <div
+                @if ($body) data-dialog-actions @if ($separator) data-separator @endif @endif
+                @class([
+                    'flex shrink-0 flex-wrap items-center justify-end gap-2 px-6 pb-6',
+                    'pt-4' => $body,
+                    'pt-6' => ! $body,
+                    'max-medium:min-h-14 max-medium:pt-2 max-medium:pb-2' => $fullscreen,
+                ])
+            >
                 {{ $actions }}
             </div>
         @endisset
diff --git a/tests/Feature/Components/OverlayTest.php b/tests/Feature/Components/OverlayTest.php
index 7d6c68a6..9c048aa8 100644
--- a/tests/Feature/Components/OverlayTest.php
+++ b/tests/Feature/Components/OverlayTest.php
@@ -1,5 +1,6 @@
 <?php
 
+use Illuminate\Support\Facades\File;
 use Livewire\Component;
 use Livewire\Livewire;
 
@@ -50,21 +51,98 @@ it('keeps a full-screen dialog\'s subtitle on a phone, where its bar carries the
     expect($html)
         ->toMatch('/<h2 id="[^"]+-title" class="type-headline-sm max-medium:hidden">/')
         ->toMatch('/<p id="[^"]+-subtitle" class="type-body-md text-on-surface-variant mt-4 max-medium:mt-0">Scan the code<\/p>/')
-        ->not->toContain('<div class="shrink-0 px-6 pt-6 max-medium:hidden">')
-        ->and((string) $this->blade('<x-modal title="Help" fullscreen>Text</x-modal>'))->toContain('<div class="shrink-0 px-6 pt-6 max-medium:hidden">')
+        ->not->toContain('class="shrink-0 px-6 pt-6 pb-2 max-medium:hidden"')
+        ->and((string) $this->blade('<x-modal title="Help" fullscreen>Text</x-modal>'))->toContain('class="shrink-0 px-6 pt-6 pb-2 max-medium:hidden"')
         ->and((string) $this->blade('<x-modal subtitle="Only a subtitle">Text</x-modal>'))->toMatch('/<p id="[^"]+-subtitle" class="type-body-md text-on-surface-variant">Only a subtitle<\/p>/');
 });
 
 it('pins a dialog\'s headline and actions and scrolls only the body between them', function () {
-    $html = (string) $this->blade('<x-modal title="Terms" subtitle="Please read" separator>Body<x-slot:actions><button>Agree</button></x-slot:actions></x-modal>');
+    $html = (string) $this->blade('<x-modal title="Terms" subtitle="Please read">Body<x-slot:actions><button>Agree</button></x-slot:actions></x-modal>');
 
     expect($html)
         ->toContain('overflow-hidden rounded-corner-xl bg-surface-container-high shadow-elevation-3')
         ->not->toContain('overflow-y-auto rounded-corner-xl')
-        ->toContain('<div class="shrink-0 px-6 pt-6">')
-        ->toMatch('/<div id="[^"]+-body" class="min-h-0 flex-1 overflow-y-auto px-6 type-body-md text-on-surface-variant pt-4">/')
-        ->toContain('flex shrink-0 flex-wrap items-center justify-end gap-2 px-6 pt-6 pb-6')
-        ->and(substr_count($html, 'role="separator"'))->toBe(2);
+        ->toMatch('/<div\s+data-dialog-head\s+class="shrink-0 px-6 pt-6 pb-2"\s*>/')
+        ->toMatch('/<div id="[^"]+-body" x-dialog-dividers class="min-h-0 flex-1 overflow-y-auto px-6 type-body-md text-on-surface-variant pt-2 pb-2">\s*<div data-dialog-content>Body<\/div>\s*<\/div>/')
+        ->toMatch('/<div\s+data-dialog-actions\s+class="flex shrink-0 flex-wrap items-center justify-end gap-2 px-6 pb-6 pt-4"\s*>/');
+});
+
+it('divides a scrolling body from its header and actions only while content is hidden past them', function () {
+    $html = (string) $this->blade('<x-modal title="Terms">Body<x-slot:actions><button>Agree</button></x-slot:actions></x-modal>');
+
+    // The script marks the dialog, which a morph leaves alone, and nothing is marked before it runs.
+    expect($html)
+        ->toContain('x-dialog-dividers')
+        ->not->toContain('data-overflow-top')
+        ->not->toContain('data-overflow-bottom')
+        ->not->toContain('data-separator')
+        ->not->toContain('role="separator"')
+        ->and(substr_count($html, 'data-dialog-head'))->toBe(1)
+        ->and(substr_count($html, 'data-dialog-actions'))->toBe(1);
+
+    expect(File::get(__DIR__.'/../../../resources/css/components/dialog.css'))
+        ->toContain('dialog[data-overflow-top] > * > [data-dialog-head]::after')
+        ->toContain('dialog[data-overflow-bottom] > * > [data-dialog-actions]::before')
+        ->toContain('background-color: var(--md-sys-color-outline-variant);')
+        ->toContain('height: 1px;')
+        ->toContain('position: absolute;')
+        // A token that reduced motion sets to zero, so then the rule appears without a fade.
+        ->toContain('transition: opacity var(--md-sys-motion-effects-fast-duration) var(--md-sys-motion-effects-fast);')
+        ->and(File::get(__DIR__.'/../../../resources/css/material.css'))->toContain("@import './components/dialog.css';")
+        ->and(File::get(__DIR__.'/../../../resources/js/material.js'))->toContain("import './dialog.js'")
+        ->and(File::get(__DIR__.'/../../../resources/js/dialog.js'))
+        ->toContain("directive('dialog-dividers'")
+        ->toContain('new ResizeObserver(measure)')
+        ->toContain('[data-dialog-content]');
+});
+
+it('draws the dividers whatever the scroll with separator, and only where a body has neighbours', function () {
+    expect((string) $this->blade('<x-modal title="Terms" separator>Body<x-slot:actions><button>Agree</button></x-slot:actions></x-modal>'))
+        ->toMatch('/<div\s+data-dialog-head\s+data-separator\s+class="shrink-0 px-6 pt-6 pb-2"/')
+        ->toMatch('/<div\s+data-dialog-actions\s+data-separator\s+class="flex shrink-0/')
+        ->and(File::get(__DIR__.'/../../../resources/css/components/dialog.css'))
+        ->toContain('[data-dialog-head][data-separator]::after')
+        ->toContain('[data-dialog-actions][data-separator]::before');
+
+    // Without a body there is nothing to divide, and the header keeps M3's 24dp to the actions.
+    expect((string) $this->blade('<x-modal title="Discard the draft?" separator><x-slot:actions><button>Discard</button></x-slot:actions></x-modal>'))
+        ->not->toContain('data-dialog-head')
+        ->not->toContain('data-dialog-actions')
+        ->not->toContain('data-separator')
+        ->not->toContain('x-dialog-dividers')
+        ->toContain('class="shrink-0 px-6 pt-6"')
+        ->toContain('flex shrink-0 flex-wrap items-center justify-end gap-2 px-6 pb-6 pt-6"');
+
+    // No header: the body keeps its 24dp top and only the actions carry a rule; no actions: its 24dp bottom.
+    expect((string) $this->blade('<x-modal>Body<x-slot:actions><button>OK</button></x-slot:actions></x-modal>'))
+        ->not->toContain('data-dialog-head')
+        ->toContain('data-dialog-actions')
+        ->toContain('text-on-surface-variant pt-6 pb-2"')
+        ->and((string) $this->blade('<x-modal title="About">Body</x-modal>'))
+        ->toContain('data-dialog-head')
+        ->not->toContain('data-dialog-actions')
+        ->toContain('text-on-surface-variant pt-2 pb-6"');
+});
+
+it('puts a full-screen dialog\'s top divider under its bar on a phone, unless the header stays there', function () {
+    $titled = (string) $this->blade('<x-modal title="Share settings" fullscreen>Body<x-slot:actions><button>Save</button></x-slot:actions></x-modal>');
+
+    // Both carry the hook: the bar shows only below medium, and this header only from it.
+    expect($titled)
+        ->toMatch('/<div\s+data-dialog-head\s+class="flex h-14 shrink-0 items-center gap-1 px-1 medium:hidden"/')
+        ->toMatch('/<div\s+data-dialog-head\s+class="shrink-0 px-6 pt-6 pb-2 max-medium:hidden"/')
+        ->toContain('text-on-surface-variant pt-2 max-medium:pt-4 pb-2"')
+        ->and(substr_count($titled, 'data-dialog-head'))->toBe(2);
+
+    // A subtitle keeps the header on a phone, so the rule stays under it rather than under the bar.
+    $subtitled = (string) $this->blade('<x-modal title="Share settings" subtitle="Who can see it" fullscreen>Body</x-modal>');
+
+    expect($subtitled)
+        ->toMatch('/<div\s+class="flex h-14 shrink-0 items-center gap-1 px-1 medium:hidden"/')
+        ->toContain('text-on-surface-variant pt-2 pb-6"')
+        ->and(substr_count($subtitled, 'data-dialog-head'))->toBe(1)
+        ->and((string) $this->blade('<x-modal fullscreen>Body</x-modal>'))
+        ->toMatch('/<div\s+data-dialog-head\s+class="flex h-14 shrink-0/');
 });
 
 it('is an alert dialog when it interrupts, and describes itself by its subtitle', function () {
@@ -85,7 +163,9 @@ it('is an alert dialog when it interrupts, and describes itself by its subtitle'
 it('gives a full-screen dialog M3\'s 56px header and action bar', function () {
     expect((string) $this->blade('<x-modal title="Share settings" fullscreen>Body<x-slot:actions><button>Save</button></x-slot:actions></x-modal>'))
         ->toContain('flex h-14 shrink-0 items-center gap-1 px-1 medium:hidden')
-        ->toContain('max-medium:min-h-14 max-medium:border-t max-medium:border-outline-variant max-medium:pt-2 max-medium:pb-2');
+        ->toContain('max-medium:min-h-14 max-medium:pt-2 max-medium:pb-2')
+        // Its rule follows the scroll, like any dialog's, instead of always showing.
+        ->not->toContain('max-medium:border-t');
 });
 
 it('leaves a pane open on Escape unless it is asked to close then too', function () {