GiteaMailTemplates/themes/horizon/mail/user/auth/activate_email.tmpl

<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <meta name="x-apple-disable-message-reformatting" />

  <title>
    {{.locale.Tr "mail.activate_email.title" (.DisplayName|DotEscape)}}
  </title>

  <style type="text/css">
    /* Base */
    body,.ExternalClass,.ReadMsgBody { background-color:#f4f6f9 }
    .email-wrap { max-width:600px;margin:20px auto;font-family:’Helvetica Neue’,Helvetica,Arial,sans-serif }

    /* Header */
    .email-logo { display:inline-block;vertical-align:middle;margin-right:12px;border:0;outline:none }
    .email-brand { font-size:22px;font-weight:600;color:#1e293b;letter-spacing:-0.2px;vertical-align:middle }
    .email-header { padding:28px 32px 16px;border-bottom:1px solid #eef2f6;background:#ffffff;border-radius:12px 12px 0 0 }

    /* Card */
    .email-card { padding:32px 32px 24px;color:#334155;background:#ffffff }
    .email-heading { margin:0 0 16px;font-size:16px;line-height:1.5;color:#1e293b }
    .email-text { margin:0 0 20px;font-size:16px;line-height:1.5;color:#334155 }
    .email-subtext { margin:0 0 20px;font-size:16px;line-height:1.5;color:#334155 }

    /* Divider */
    .email-divider { height:1px;background:linear-gradient(90deg,transparent,#e2e8f0,transparent);margin:16px 0 8px }

    /* Button */
    .email-btn-row { padding:0;text-align:center }
    .email-btn { display:inline-block;padding:14px 36px;font-size:16px;font-weight:500;color:#ffffff;text-decoration:none;background:#1e88e5;border-radius:48px;border:1px solid #1e88e5;letter-spacing:0.3px;text-align:center }
    .email-btn-table { margin:28px 0 24px;border-collapse:separate }

    /* Fallback link */
    .email-link-box { border:1px solid #e2e8f0;background:#f8fafc;border-radius:10px }
    .email-link-label { margin:0 0 8px;font-size:14px;color:#475569;line-height:1.5 }
    .email-link-url { margin:0;font-size:14px;font-family:monospace;color:#1e88e5;background:#ffffff;padding:10px 12px;border-radius:6px;border:1px solid #e2e8f0;word-break:break-all }

    /* Footer */
    .email-footer { padding:20px 32px 28px;background:#f9fbfd;border-top:1px solid #eef2f6;text-align:left;border-radius:0 0 12px 12px }
    .email-footer-text { margin:0;font-size:14px;color:#64748b }
    .email-footer-link { color:#1e88e5;text-decoration:none;font-weight:500;border-bottom:1px dotted #b9d5f0 }

    /* Typography utilities */
    .card-body a { color:#1e88e5!important;text-decoration:none!important;font-weight:500!important }

    /* Responsive */
    @media only screen and (max-width:480px) {
      .email-header { padding:20px 20px 12px!important }
      .email-card { padding:24px 20px 16px!important }
      .email-btn-row { padding:0!important }
      .email-footer { padding:16px 20px 24px!important }
    }
  </style>
</head>

<body style="margin:0;padding:0;background:#f4f6f9;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%;">
  <center style="width:100%;table-layout:fixed;">
    <table width="100%" cellpadding="0" cellspacing="0" border="0" style="max-width:600px;background:#ffffff;border-radius:12px;box-shadow:0 4px 12px rgba(0,0,0,0.05);overflow:hidden;" class="email-wrap">

      <!-- Floating Title -->
      <tr>
        <td class="email-header">

          <img src="{{AppUrl}}assets/img/favicon.png" alt="logo" width="32" height="32" class="email-logo" />
          <span class="email-brand">{{AppName}}</span>

        </td>
      </tr>

      <!-- Card -->
      <tr>
        <td class="email-card card-body">

          <p class="email-heading">
            {{.locale.Tr "mail.hi_user_x" (.DisplayName|DotEscape)}}
          </p>

          <p class="email-text">
            {{.locale.Tr "mail.activate_email.text" .ActiveCodeLives}}
          </p>

        </td>
      </tr>

      <!-- Divider -->
      <tr>
        <td class="email-divider"></td>
      </tr>

      <!-- Button & Link -->
      <tr>
        <td class="email-btn-row">

          {{$activate_url := printf "%suser/activate_email?code=%s&email=%s" AppUrl (QueryEscape .Code) (QueryEscape .Email)}}

          <table border="0" cellpadding="0" cellspacing="0" width="100%" class="email-btn-table">
            <tr>
              <td align="center">
                <a href="{{$activate_url}}" class="email-btn">{{.locale.Tr "mail.activate_email"}}</a>
              </td>
            </tr>
          </table>

          <table width="100%" cellpadding="0" cellspacing="0" border="0" class="email-link-box">
            <tr>
              <td style="padding:16px 18px;">
                <p class="email-link-label">{{.locale.Tr "mail.link_not_working_do_paste"}}</p>
                <p class="email-link-url">{{$activate_url}}</p>
              </td>
            </tr>
          </table>

        </td>
      </tr>

      <!-- Footer -->
      <tr>
        <td class="email-footer">

          <p class="email-footer-text">
            &copy;
            <a href="{{AppUrl}}" class="email-footer-link">{{AppName}}</a>
            &mdash; Gitea Mail Templates
          </p>

        </td>
      </tr>

    </table>
  </center>
</body>
</html>