feat(deck): mobile support — scrollable slides, swipe, desktop notice

Content-heavy slides were clipped on phones (fixed h-dvh + centered
overflow-hidden collided with the top/bottom bars). SlideFrame now
scrolls and top-aligns below md (clearing the header/controls), while
desktop keeps the centered, full-bleed look unchanged. Add horizontal
touch-swipe navigation (vertical scroll still works). Add a shadcn-vue
Alert component and show a mobile-only "Best viewed on desktop" notice
on the home slide; keyboard hint is desktop-only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/ui/alert/Alert.vue

@@ -0,0 +1,16 @@
+<script setup lang="ts">
+import type { HTMLAttributes } from 'vue'
+import { cn } from '@/lib/utils'
+import { type AlertVariants, alertVariants } from '.'
+
+const props = defineProps<{
+  class?: HTMLAttributes['class']
+  variant?: AlertVariants['variant']
+}>()
+</script>
+
+<template>
+  <div data-slot="alert" role="alert" :class="cn(alertVariants({ variant }), props.class)">
+    <slot />
+  </div>
+</template>

src/components/ui/alert/AlertDescription.vue

@@ -0,0 +1,12 @@
+<script setup lang="ts">
+import type { HTMLAttributes } from 'vue'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<{ class?: HTMLAttributes['class'] }>()
+</script>
+
+<template>
+  <div data-slot="alert-description" :class="cn('text-sm [&_p]:leading-relaxed', props.class)">
+    <slot />
+  </div>
+</template>

src/components/ui/alert/AlertTitle.vue

@@ -0,0 +1,12 @@
+<script setup lang="ts">
+import type { HTMLAttributes } from 'vue'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<{ class?: HTMLAttributes['class'] }>()
+</script>
+
+<template>
+  <h5 data-slot="alert-title" :class="cn('mb-1 font-medium leading-none tracking-tight', props.class)">
+    <slot />
+  </h5>
+</template>

src/components/ui/alert/index.ts

@@ -0,0 +1,23 @@
+import { cva, type VariantProps } from 'class-variance-authority'
+
+export { default as Alert } from './Alert.vue'
+export { default as AlertTitle } from './AlertTitle.vue'
+export { default as AlertDescription } from './AlertDescription.vue'
+
+export const alertVariants = cva(
+  'relative w-full rounded-lg border p-4 [&>svg~*]:pl-7 [&>svg+div]:translate-y-[-3px] [&>svg]:absolute [&>svg]:left-4 [&>svg]:top-4 [&>svg]:text-foreground',
+  {
+    variants: {
+      variant: {
+        default: 'bg-background text-foreground',
+        destructive:
+          'border-destructive/50 text-destructive dark:border-destructive [&>svg]:text-destructive',
+      },
+    },
+    defaultVariants: {
+      variant: 'default',
+    },
+  },
+)
+
+export type AlertVariants = VariantProps<typeof alertVariants>

src/deck/Deck.vue

@@ -49,6 +49,22 @@ const slides = [
 const { index, direction, goto, next, prev, isFirst, isLast } = useDeck(slides.length)
 const current = computed(() => slides[index.value])
 const transitionName = computed(() => (direction.value === 1 ? 'slide-next' : 'slide-prev'))
+
+// swipe navigation (touch) — horizontal only, so vertical scrolling still works
+let touchX = 0
+let touchY = 0
+function onTouchStart(e: TouchEvent) {
+  touchX = e.changedTouches[0].clientX
+  touchY = e.changedTouches[0].clientY
+}
+function onTouchEnd(e: TouchEvent) {
+  const dx = e.changedTouches[0].clientX - touchX
+  const dy = e.changedTouches[0].clientY - touchY
+  if (Math.abs(dx) > 60 && Math.abs(dx) > Math.abs(dy) * 1.5) {
+    if (dx < 0) next()
+    else prev()
+  }
+}
 </script>
 
 <template>
@@ -75,7 +91,7 @@ const transitionName = computed(() => (direction.value === 1 ? 'slide-next' : 's
     </header>
 
     <!-- slide stage -->
-    <main class="h-full w-full">
+    <main class="h-full w-full" @touchstart.passive="onTouchStart" @touchend.passive="onTouchEnd">
       <Transition :name="transitionName" mode="out-in">
         <KeepAlive>
           <component :is="current.component" :key="current.id" class="h-full w-full" />

src/deck/components/SlideFrame.vue

@@ -10,8 +10,8 @@ defineProps<{
 
 <template>
   <section
-    class="mx-auto flex h-full w-full max-w-6xl flex-col px-8 py-14 sm:px-14 lg:px-20"
+    class="mx-auto flex h-full w-full max-w-6xl flex-col overflow-y-auto px-5 pt-20 pb-24 md:overflow-visible md:px-14 md:py-14 lg:px-20"
-    :class="center ? 'items-center justify-center text-center' : 'justify-center'"
+    :class="[center ? 'items-center text-center' : '', 'justify-start md:justify-center']"
   >
     <p
       v-if="kicker"

src/deck/slides/TitleSlide.vue

@@ -1,6 +1,8 @@
 <script setup lang="ts">
+import { Monitor } from '@lucide/vue'
 import SlideFrame from '../components/SlideFrame.vue'
 import PlaceholderBadge from '../components/PlaceholderBadge.vue'
+import { Alert, AlertTitle, AlertDescription } from '@/components/ui/alert'
 import { brand, surfaceEntities, accentText } from '../data'
 </script>
 
@@ -40,7 +42,16 @@ import { brand, surfaceEntities, accentText } from '../data'
         Raising now · {{ brand.firstNode }}
       </span>
 
-      <p class="mt-10 text-xs text-fg-muted">
+      <!-- mobile-only: this deck is built for desktop -->
+      <Alert class="mt-8 max-w-sm border-amber-400/40 bg-amber-400/10 text-left md:hidden">
+        <Monitor class="size-4" />
+        <AlertTitle>Best viewed on desktop</AlertTitle>
+        <AlertDescription class="text-fg-muted">
+          This investment deck is designed for a larger screen. Swipe to browse the highlights.
+        </AlertDescription>
+      </Alert>
+
+      <p class="mt-10 hidden text-xs text-fg-muted md:block">
         Use <kbd class="rounded border border-line-2 px-1.5 py-0.5">→</kbd> /
         <kbd class="rounded border border-line-2 px-1.5 py-0.5">←</kbd> to navigate
       </p>