Email Template Design Skill

Email Template Design

Design production-ready HTML email templates using table-based layouts and inline CSS for maximum email client compatibility.

Workflow

Clarify purpose - Determine the email type (marketing, transactional, lifecycle) and brand context
Select base template - Start from an asset template in assets/ or build from scratch using the patterns below
Build structure - Use table-based layout with the boilerplate from assets/base.html
Style inline - Apply all CSS as inline styles; use <style> block only as progressive enhancement
Test compatibility - Review against the client quirks in references/client-compatibility.md
Optimize - Compress images, add alt text, verify dark mode, ensure accessibility

Email Type Selection

| Type | Key characteristics | Template asset | |------|-------------------|----------------| | Marketing / Newsletter | Hero image, CTA buttons, multi-section content | assets/marketing.html | | Transactional | Data-driven, minimal design, clear information hierarchy | assets/transactional.html | | Lifecycle / Drip | Personal tone, single CTA, storytelling flow | assets/lifecycle.html |

Core Architecture

Every email template follows this skeleton:

<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="x-apple-disable-message-reformatting">
  <meta name="format-detection" content="telephone=no,address=no,email=no,date=no,url=no">
  <title>{{email_title}}</title>
  <!--[if mso]>
  <noscript><xml>
    <o:OfficeDocumentSettings>
      <o:AllowPNG/>
      <o:PixelPerInch>96</o:PixelPerInch>
    </o:OfficeDocumentSettings>
  </xml></noscript>
  <![endif]-->
  <style>
    /* Reset — progressive enhancement only */
    table, td { mso-table-lspace:0pt; mso-table-rspace:0pt; }
    img { -ms-interpolation-mode:bicubic; border:0; height:auto; line-height:100%; outline:none; text-decoration:none; }
    body { margin:0; padding:0; width:100%!important; -webkit-text-size-adjust:100%; -ms-text-size-adjust:100%; }

    /* Dark mode */
    @media (prefers-color-scheme: dark) {
      .dark-bg { background-color: #1a1a2e !important; }
      .dark-text { color: #e0e0e0 !important; }
    }

    /* Responsive */
    @media only screen and (max-width: 600px) {
      .stack-column { display: block !important; width: 100% !important; max-width: 100% !important; }
      .mobile-padding { padding-left: 16px !important; padding-right: 16px !important; }
      .mobile-full-width { width: 100% !important; }
      .mobile-hide { display: none !important; }
      .mobile-center { text-align: center !important; }
    }
  </style>
</head>
<body style="margin:0; padding:0; background-color:#f4f4f4;">
  <!-- Preview text (hidden preheader) -->
  <div style="display:none; max-height:0; overflow:hidden;">
    {{preview_text}}&#847;&zwnj;&nbsp;&#847;&zwnj;&nbsp;&#847;&zwnj;&nbsp;
  </div>

  <!-- Outer wrapper -->
  <table role="presentation" width="100%" cellpadding="0" cellspacing="0" border="0" style="background-color:#f4f4f4;">
    <tr>
      <td align="center" style="padding: 20px 0;">
        <!-- Inner container (600px max) -->
        <table role="presentation" width="600" cellpadding="0" cellspacing="0" border="0" class="mobile-full-width" style="background-color:#ffffff; border-radius:8px; overflow:hidden;">
          <!-- CONTENT ROWS GO HERE -->
        </table>
      </td>
    </tr>
  </table>
</body>
</html>

Essential Patterns

CTA Buttons (Outlook-safe)

<table role="presentation" cellpadding="0" cellspacing="0" border="0" style="margin:0 auto;">
  <tr>
    <td align="center" style="border-radius:6px; background-color:#2563eb;">
      <!--[if mso]>
      <v:roundrect xmlns:v="urn:schemas-microsoft-com:vml" href="{{url}}" style="height:44px; width:200px; v-text-anchor:middle;" arcsize="14%" fill="true" stroke="false">
        <v:fill type="tile" color="#2563eb"/>
        <v:textbox inset="0,0,0,0"><center style="color:#ffffff; font-family:Arial,sans-serif; font-size:16px; font-weight:bold;">Button Text</center></v:textbox>
      </v:roundrect>
      <![endif]-->
      <!--[if !mso]><!-->
      <a href="{{url}}" style="display:inline-block; padding:12px 32px; font-family:Arial,Helvetica,sans-serif; font-size:16px; font-weight:bold; color:#ffffff; text-decoration:none; border-radius:6px; background-color:#2563eb;">Button Text</a>
      <!--<![endif]-->
    </td>
  </tr>
</table>

Two-Column Layout (responsive)

<table role="presentation" width="100%" cellpadding="0" cellspacing="0" border="0">
  <tr>
    <td style="padding: 20px;">
      <!--[if mso]><table role="presentation" width="100%" cellpadding="0" cellspacing="0" border="0"><tr><td width="280" valign="top"><![endif]-->
      <div class="stack-column" style="display:inline-block; width:280px; vertical-align:top;">
        <!-- Left column content -->
      </div>
      <!--[if mso]></td><td width="20"></td><td width="280" valign="top"><![endif]-->
      <div class="stack-column" style="display:inline-block; width:280px; vertical-align:top;">
        <!-- Right column content -->
      </div>
      <!--[if mso]></td></tr></table><![endif]-->
    </td>
  </tr>
</table>

Hero Image

<tr>
  <td style="padding:0; line-height:0;">
    <img src="{{hero_image_url}}" alt="{{hero_alt}}" width="600" style="display:block; width:100%; max-width:600px; height:auto;" class="mobile-full-width">
  </td>
</tr>

Design Rules

600px max width for the content container
All critical styles inline — <style> blocks are for progressive enhancement only (resets, dark mode, responsive)
Tables for layout — use role="presentation" on every layout table
System-safe font stacks — font-family: Arial, Helvetica, sans-serif; or Georgia, 'Times New Roman', serif;. Web fonts via @import work in Apple Mail, iOS Mail, and some Android clients only
Images: always set explicit width, height:auto, display:block, border:0, and meaningful alt text
Backgrounds: use inline background-color; background images require VML fallback for Outlook — see references/client-compatibility.md
Spacing: use padding on <td> cells, never margin on tables
Links: always use absolute URLs with https://
Preheader text: hidden preview text improves open rates; pad with ͏&zwnj;  to prevent email clients from pulling body content

Accessibility

Use semantic lang attribute on <html>
Add role="presentation" to all layout tables
Provide descriptive alt text for all images
Maintain minimum 4.5:1 contrast ratio for text
Use at least 14px font size for body text
Structure content in logical reading order (not reliant on visual layout)
Include a plain-text version or web-view link

Dark Mode

Support three strategies (apply all):

@media (prefers-color-scheme: dark) in <style> — works in Apple Mail, Outlook.com
color-scheme: light dark meta tag and CSS property — opts into native dark mode handling
Transparent images — use PNGs with transparency so logos adapt to dark backgrounds; provide light/dark logo variants when possible

For full dark mode quirks per client, see references/client-compatibility.md.

Pre-Send Checklist

[ ] All CSS is inline (use a CSS inliner tool if needed)
[ ] Preview text is set and padded
[ ] All images have alt, width, display:block
[ ] CTA buttons use VML fallback for Outlook
[ ] Links are absolute https:// URLs
[ ] Responsive breakpoint at 600px tested
[ ] Dark mode classes applied to key elements
[ ] Unsubscribe link present (required for marketing emails by CAN-SPAM / GDPR)
[ ] Plain-text fallback available
[ ] Total email size under 102KB (Gmail clipping threshold)

Agent Skills: Email Template Design

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