erpnext/templates/emails/birthday_reminder.html

<div class="gray-container text-center">
	<div>
		{% for person in birthday_persons %}
		<span class="avatar avatar-small " title="Mitali">
			<span class="avatar-frame standard-image" style="{% if person.image %}background-image: url({{person.image}}); {% endif %}  margin-right: 5px;"
				title={{person.name}}>
				{% if not person.image %} {{ person.name[:1] }} {% endif %}
			</span>
		</span>
		{% endfor %}
	</div>
	<div style="margin-top: 15px">
		<span>{{ reminder_text }}</span>
		<p class="text-muted">{{ message }}</p>
	</div>
</div>