App Store Screenshots Generator

Overview

Build a Next.js page that renders iOS App Store screenshots as advertisements (not UI showcases) and exports them via html-to-image at Apple's required resolutions. Screenshots are the single most important conversion asset on the App Store.

Reads

• brand/creative-kit.md — Brand colors, fonts, logo paths
• brand/voice-profile.md — Copy tone and personality
• brand/positioning.md — Positioning angles for headline direction

On Activation

1. Read brand/creative-kit.md for colors, fonts, and logo.
2. Read brand/voice-profile.md for copy tone — this shapes headline style (playful vs. professional vs. minimal).
3. Read brand/positioning.md for positioning angles — the primary angle informs the hero slide headline direction.
4. If brand/ files don't exist, the skill works at zero context. Step 1 gathers everything needed.

Core Principle

Screenshots are advertisements, not documentation. Every screenshot sells one idea. If you're showing UI, you're doing it wrong — you're selling a feeling, an outcome, or killing a pain point.

Step 1: Ask the User

If brand/ files provided answers (colors, fonts, voice tone), confirm them with the user and skip those questions. Only ask what's genuinely unknown. Do not proceed until you have all answers:

Required

1. App screenshots — "Where are your app screenshots? (PNG files of actual device captures)"
2. App icon — "Where is your app icon PNG?"
3. Brand colors — "What are your brand colors? (accent color, text color, background preference)"
4. Font — "What font does your app use? (or what font do you want for the screenshots?)"
5. Feature list — "List your app's features in priority order. What's the #1 thing your app does?"
6. Number of slides — "How many screenshots do you want? (Apple allows up to 10)"
7. Style direction — "What style do you want? Examples: warm/organic, dark/moody, clean/minimal, bold/colorful, gradient-heavy, flat. Share App Store screenshot references if you have any."

Optional

1. iPad screenshots — "Do you also have iPad screenshots? If so, we'll generate iPad App Store screenshots too (recommended for universal apps)."
2. Component assets — "Do you have any UI element PNGs (cards, widgets, etc.) you want as floating decorations? If not, that's fine — we'll skip them."
3. Additional instructions — "Any specific requirements, constraints, or preferences?"

Derived from answers (do NOT ask — decide yourself)

Based on the user's style direction, brand colors, and app aesthetic, decide:

• Background style: gradient direction, colors, whether light or dark base
• Decorative elements: blobs, glows, geometric shapes, or none — match the style
• Dark vs light slides: how many of each, which features suit dark treatment
• Typography treatment: weight, tracking, line height — match the brand personality
• Color palette: derive text colors, secondary colors, shadow tints from the brand colors

IMPORTANT: If the user gives additional instructions at any point during the process, follow them. User instructions always override skill defaults.

Step 2: Set Up the Project

Detect Package Manager

Check what's available, use this priority: bun > pnpm > yarn > npm

# Check in order
which bun && echo "use bun" || which pnpm && echo "use pnpm" || which yarn && echo "use yarn" || echo "use npm"

Scaffold (if no existing Next.js project)

# With bun:
bunx create-next-app@latest . --typescript --tailwind --app --src-dir --no-eslint --import-alias "@/*"
bun add html-to-image

# With pnpm:
pnpx create-next-app@latest . --typescript --tailwind --app --src-dir --no-eslint --import-alias "@/*"
pnpm add html-to-image

# With yarn:
yarn create next-app . --typescript --tailwind --app --src-dir --no-eslint --import-alias "@/*"
yarn add html-to-image

# With npm:
npx create-next-app@latest . --typescript --tailwind --app --src-dir --no-eslint --import-alias "@/*"
npm install html-to-image

Copy the Phone Mockup

The skill includes a pre-measured iPhone mockup at mockup.png (co-located with this SKILL.md). Copy it to the project's public/ directory. The mockup file is in the same directory as this skill file. No iPad mockup is needed — the iPad frame is CSS-only.

File Structure

project/
├── public/
│   ├── mockup.png              # iPhone frame (included with skill)
│   ├── app-icon.png            # User's app icon
│   ├── screenshots/            # iPhone app screenshots
│   │   ├── home.png
│   │   ├── feature-1.png
│   │   └── ...
│   └── screenshots-ipad/       # iPad app screenshots (optional)
│       ├── home.png
│       ├── feature-1.png
│       └── ...
├── src/app/
│   ├── layout.tsx              # Font setup
│   └── page.tsx                # The screenshot generator (single file)
└── package.json

Note: No iPad mockup PNG is needed — the iPad frame is rendered with CSS (see iPad Mockup Component below).

The entire generator is a single `page.tsx` file. No routing, no extra layouts, no API routes.

Font Setup

// src/app/layout.tsx
import { YourFont } from "next/font/google"; // Use whatever font the user specified
const font = YourFont({ subsets: ["latin"] });

export default function Layout({ children }: { children: React.ReactNode }) {
  return <html><body className={font.className}>{children}</body></html>;
}

Step 3: Plan the Slides

Screenshot Framework (Narrative Arc)

Adapt this framework to the user's requested slide count. Not all slots are required — pick what fits:

Rules:

• Each slide sells ONE idea. Never two features on one slide.
• Vary layouts across slides — never repeat the same template structure.
• Include 1-2 contrast slides (inverted bg) for visual rhythm.

Step 4: Write Copy FIRST

Get all headlines approved before building layouts. Bad copy ruins good design.

The Iron Rules

1. One idea per headline. Never join two things with "and."
2. Short, common words. 1-2 syllables. No jargon unless it's domain-specific.
3. 3-5 words per line. Must be readable at thumbnail size in the App Store.
4. Line breaks are intentional. Control where lines break with <br />.

Three Approaches (pick one per slide)

What NEVER Works

• Feature lists as headlines: "Log every item with tags, categories, and notes"
• Two ideas joined by "and": "Track X and never miss Y"
• Compound clauses: "Save and customize X for every Y you own"
• Vague aspirational: "Every item, tracked"
• Marketing buzzwords: "AI-powered tips" (unless it's actually AI)

Copy Process

1. Write 3 options per slide using the three approaches
2. Read each at arm's length — if you can't parse it in 1 second, it's too complex
3. Check: does each line have 3-5 words? If not, adjust line breaks
4. Present options to the user with reasoning for each

Reference Apps for Copy Style

• Raycast — specific, descriptive, one concrete value per slide
• Turf — ultra-simple action verbs, conversational
• Mela / Notion — warm, minimal, elegant

Step 5: Build the Page

Architecture

page.tsx
├── Constants (IPHONE_W/H, IPAD_W/H, SIZES, design tokens)
├── Phone component (mockup PNG with screen overlay)
├── IPad component (CSS-only frame with screen overlay)
├── Caption component (label + headline, accepts canvasW for scaling)
├── Decorative components (blobs, glows, shapes — based on style direction)
├── iPhoneSlide1..N components (one per slide)
├── iPadSlide1..N components (same designs, adjusted for iPad proportions)
├── IPHONE_SCREENSHOTS / IPAD_SCREENSHOTS arrays (registries)
├── ScreenshotPreview (ResizeObserver scaling + hover export)
└── ScreenshotsPage (grid + device toggle + size dropdown + export logic)

Export Sizes (Apple Required, portrait)

#### iPhone

const IPHONE_SIZES = [
  { label: '6.9"', w: 1320, h: 2868 },
  { label: '6.5"', w: 1284, h: 2778 },
  { label: '6.3"', w: 1206, h: 2622 },
  { label: '6.1"', w: 1125, h: 2436 },
] as const;

Design at the LARGEST size (1320x2868) and scale down for export.

#### iPad (Optional)

If the user provides iPad screenshots, also generate iPad App Store screenshots:

const IPAD_SIZES = [
  { label: '13" iPad', w: 2064, h: 2752 },
  { label: '12.9" iPad Pro', w: 2048, h: 2732 },
] as const;

Design iPad slides at 2064x2752 and scale down. iPad screenshots are optional but recommended — they're required for iPad-only apps and improve listing quality for universal apps.

#### Device Toggle

When supporting both devices, add a toggle (iPhone / iPad) in the toolbar next to the size dropdown. The size dropdown should switch between iPhone and iPad sizes based on the selected device. Support a ?device=ipad URL parameter for headless/automated capture workflows.

Rendering Strategy

Each screenshot is designed at full resolution (1320x2868px). Two copies exist:

1. Preview: CSS transform: scale() via ResizeObserver to fit a grid card
2. Export: Offscreen at position: absolute; left: -9999px at true resolution

Phone Mockup Component

The included mockup.png has these pre-measured values:

const MK_W = 1022;  // mockup image width
const MK_H = 2082;  // mockup image height
const SC_L = (52 / MK_W) * 100;   // screen left offset %
const SC_T = (46 / MK_H) * 100;   // screen top offset %
const SC_W = (918 / MK_W) * 100;  // screen width %
const SC_H = (1990 / MK_H) * 100; // screen height %
const SC_RX = (126 / 918) * 100;  // border-radius x %
const SC_RY = (126 / 1990) * 100; // border-radius y %

function Phone({ src, alt, style, className = "" }: {
  src: string; alt: string; style?: React.CSSProperties; className?: string;
}) {
  return (
    <div className={`relative ${className}`}
      style={{ aspectRatio: `${MK_W}/${MK_H}`, ...style }}>
      <img src="/mockup.png" alt=""
        className="block w-full h-full" draggable={false} />
      <div className="absolute z-10 overflow-hidden"
        style={{
          left: `${SC_L}%`, top: `${SC_T}%`,
          width: `${SC_W}%`, height: `${SC_H}%`,
          borderRadius: `${SC_RX}% / ${SC_RY}%`,
        }}>
        <img src={src} alt={alt}
          className="block w-full h-full object-cover object-top"
          draggable={false} />
      </div>
    </div>
  );
}

iPad Mockup Component (CSS-Only)

Unlike the iPhone mockup which uses a pre-measured PNG frame, the iPad uses a CSS-only frame. This avoids needing a separate mockup asset and looks clean at any resolution.

Critical dimension: The frame aspect ratio must be 770/1000 so the inner screen area (92% width × 94.4% height) matches the 3:4 aspect ratio of iPad screenshots. Using incorrect proportions causes black bars or stretched screenshots.

function IPad({ src, alt, style, className = "" }: {
  src: string; alt: string; style?: React.CSSProperties; className?: string;
}) {
  return (
    <div className={`relative ${className}`}
      style={{ aspectRatio: "770/1000", ...style }}>
      <div style={{
        width: "100%", height: "100%", borderRadius: "5% / 3.6%",
        background: "linear-gradient(180deg, #2C2C2E 0%, #1C1C1E 100%)",
        position: "relative", overflow: "hidden",
        boxShadow: "inset 0 0 0 1px rgba(255,255,255,0.1), 0 8px 40px rgba(0,0,0,0.6)",
      }}>
        {/* Front camera dot */}
        <div style={{
          position: "absolute", top: "1.2%", left: "50%",
          transform: "translateX(-50%)", width: "0.9%", height: "0.65%",
          borderRadius: "50%", background: "#111113",
          border: "1px solid rgba(255,255,255,0.08)", zIndex: 20,
        }} />
        {/* Bezel edge highlight */}
        <div style={{
          position: "absolute", inset: 0, borderRadius: "5% / 3.6%",
          border: "1px solid rgba(255,255,255,0.06)",
          pointerEvents: "none", zIndex: 15,
        }} />
        {/* Screen area */}
        <div style={{
          position: "absolute", left: "4%", top: "2.8%",
          width: "92%", height: "94.4%",
          borderRadius: "2.2% / 1.6%", overflow: "hidden", background: "#000",
        }}>
          <img src={src} alt={alt}
            style={{ display: "block", width: "100%", height: "100%",
              objectFit: "cover", objectPosition: "top" }}
            draggable={false} />
        </div>
      </div>
    </div>
  );
}

iPad layout adjustments vs iPhone:

• Use width: "65-70%" for iPad mockups (vs 82-86% for iPhone) — iPad is wider relative to its height
• Two-iPad layouts work the same as two-phone layouts but with adjusted widths
• Caption font sizes should scale from canvasW (which is 2064 for iPad vs 1320 for iPhone)
• Same slide designs/copy can be reused — just swap the Phone component for IPad and adjust positioning

Typography (Resolution-Independent)

All sizing relative to canvas width W:

Phone Placement Patterns

Vary across slides — NEVER use the same layout twice in a row:

Centered phone (hero, single-feature):

bottom: 0, width: "82-86%", translateX(-50%) translateY(12-14%)

Two phones layered (comparison):

Back: left: "-8%", width: "65%", rotate(-4deg), opacity: 0.55
Front: right: "-4%", width: "82%", translateY(10%)

Phone + floating elements (only if user provided component PNGs):

Cards should NOT block the phone's main content.
Position at edges, slight rotation (2-5deg), drop shadows.
If distracting, push partially off-screen or make smaller.

"More Features" Slide (Optional)

Dark/contrast background with app icon, headline ("And so much more."), and feature pills. Can include a "Coming Soon" section with dimmer pills.

Step 6: Export

Why html-to-image, NOT html2canvas

html2canvas breaks on CSS filters, gradients, drop-shadow, backdrop-filter, and complex clipping. html-to-image uses native browser SVG serialization — handles all CSS faithfully.

Export Implementation

import { toPng } from "html-to-image";

// Before capture: move element on-screen
el.style.left = "0px";
el.style.opacity = "1";
el.style.zIndex = "-1";

const opts = { width: W, height: H, pixelRatio: 1, cacheBust: true };

// CRITICAL: Double-call trick — first warms up fonts/images, second produces clean output
await toPng(el, opts);
const dataUrl = await toPng(el, opts);

// After capture: move back off-screen
el.style.left = "-9999px";
el.style.opacity = "";
el.style.zIndex = "";

Key Rules

• Double-call trick: First toPng() loads fonts/images lazily. Second produces clean output. Without this, exports are blank.
• On-screen for capture: Temporarily move to left: 0 before calling toPng.
• Offscreen container: Use position: absolute; left: -9999px (not fixed).
• Resizing: Load data URL into Image, draw onto canvas at target size.
• 300ms delay between sequential exports.
• Set fontFamily on the offscreen container.
• Numbered filenames: Prefix exports with zero-padded index so they sort correctly: 01-hero-1320x2868.png, 02-freshness-1320x2868.png, etc. Use String(index + 1).padStart(2, "0").

Common Mistakes

Step 7: Completion Summary

Present the final deliverable to the user:

## App Store Screenshots Complete

### Files Created
| File | Size | Device | Purpose |
|------|------|--------|---------|
| 01-hero-1320x2868.png | [size] | iPhone 6.9" | Hero slide |
| 01-hero-1284x2778.png | [size] | iPhone 6.5" | Hero slide |
| ... | ... | ... | ... |

### How to Upload
1. Open App Store Connect → Your App → App Store tab
2. Scroll to "Screenshots" section
3. Upload each size set to its corresponding device slot
4. iPhone 6.9" screenshots auto-apply to 6.7" and 6.3"
5. iPhone 6.1" is only needed for older device support

### Regenerating
Run the Next.js app (`bun dev`) and use the export buttons to regenerate at any size.
The generator is a permanent asset — update screenshots anytime by swapping PNGs in `public/screenshots/`.