A small newsletter usually has one image that readers see every single issue: the header at the top of the email. It shows up in inboxes, in the web archive and often as the preview image when someone shares a post. When every header looks like it came from a different place, the newsletter feels improvised. When they share a clear style, readers recognise the issue before they read the subject line.
You don't need a designer on retainer to get there. You need a short written style, a few reusable reference images and a quick check before each send. This guide walks through a simple routine that works whether you edit headers by hand or with a text-prompt image editor.
Start with the constraints of email
Newsletter headers live in a harder environment than social posts, so plan around that first.
- Width: most email layouts are around 600 pixels wide. Export at twice that width (about 1200 pixels) so the image stays sharp on high-density screens.
- Shape: a wide, short banner, such as 1200 by 400 or 1200 by 500 pixels, keeps the first lines of text visible without scrolling on a phone.
- File size: keep each header well under 500 KB. Large images load slowly on mobile data and some email clients clip long messages.
- Small screens: on a phone the header may be shown at roughly 350 pixels wide. Fine detail and small text inside the image disappear at that size.
- Dark mode: some email apps invert or dim colours. Very light backgrounds with thin dark lines can look muddy after inversion.
Write these numbers at the top of your style notes so every header starts from the same frame.
Write a one-paragraph style sheet
A style sheet for a newsletter can be short. Answer five questions in plain sentences:
- Palette: which two or three colours appear in every header? For example, "warm off-white, deep teal and a small accent of orange."
- Light: what kind of light do the images have? "Soft morning daylight from the left, no harsh shadows" is specific enough to repeat.
- Subject distance: are the subjects close-ups, desk-level still lifes or wide scenes? Pick one and keep it.
- Texture and finish: photographic, flat illustration or something in between? Clean or slightly grainy?
- What never appears: busy patterns behind the title, neon colours, or stock-photo handshakes. A "never" list keeps drift in check.
Keep the paragraph in the same folder as your header files. When you edit with prompts, you will reuse these phrases almost word for word.
Build a small reference set
Choose three to five headers that you think match the style best. If you are starting from scratch, make them first and treat them as the reference set. These images do two jobs: they show you what "on style" looks like, and they give you a base image to edit from when a new issue needs a header.
Many newsletters have a recurring subject, such as a desk, a mascot, a product or a place. Reusing that subject across issues is the easiest way to look consistent. Change the scene around it, not the subject itself.
Edit each new header from a reference, not from scratch
When a new issue needs a header, start from the closest reference image and describe only what changes for this topic. A text-prompt editor such as Nano Banana AI lets you write that change in plain language while asking for the rest of the image to stay the same. A prompt might look like this:
"Keep the same desk, notebook and teal mug, the same soft morning light from the left and the same off-white background. Add a small stack of seed packets next to the notebook for a gardening issue. Do not add text or extra objects."
Notice the structure: first the things that must stay, then the one change, then what to avoid. Writing the constraints out each time feels repetitive, but it is what keeps issue 30 looking like issue 3.
If a result drifts, for example if the mug turns blue or the light moves to the right, don't stack more changes on top. Go back to the reference and try a smaller, more specific instruction.
Leave room for the title
Many newsletters place the issue title or number over the header. If you do this, keep a calm area in the image where text will sit, usually the left third or the lower band. Put this rule into your style sheet: "Left 40 percent of the image stays plain background."
Add the title as live text in your email tool when you can, rather than baking it into the image. Live text stays readable for screen readers, scales on small screens and doesn't disappear when images are blocked.
Check before you send
Run a quick review on each new header:
- View it at phone width. Is the main subject still clear?
- Compare it side by side with two reference headers. Do the colours and light match?
- Send a test email to yourself and open it in both light and dark mode.
- Write short alt text that describes the image, such as "Desk with notebook, teal mug and seed packets in morning light."
- Check the file size and dimensions one more time.
Keep a simple archive
Save each final header with the issue number and date in the file name, together with the prompt or notes you used. After a few months this archive becomes your best style guide: you can see which headers worked, reuse successful prompts and notice if the style has slowly drifted.
Summary
A consistent newsletter header comes from a few small decisions made once: fixed dimensions, a short written style, a set of reference images and the habit of editing from those references with clear constraints. Each issue then only needs one change, the topic, and readers get a header they recognise at a glance.
