mail.pug: Rebuild the mail page

src/mail/mail.pug

@@ -1,4 +1,52 @@
 extends ../lib/pug/base
 
 block content
-  p This is the mail page.
+  h1 Contact me
+
+  .row
+    //- The form
+    .col-md-6
+      form#sendmail(role="form", action="/api/mail", method="post")
+        //- The sender address
+        .form-group
+          label.control-label(for="mail") Email address
+          input#mail.form-control(
+              type="email",
+              placeholder="Your address",
+              name="mail",
+              required
+          )
+
+        //- The subject line
+        .form-group
+          label.control-label(for="subject") Subject
+          input#subject.form-control(
+              type="text",
+              placeholder="E.g. There's a typo on your home page!",
+              name="subject",
+              autocomplete="off",
+              required
+          )
+
+        //- The message box
+        .form-group
+          label.control-label(for="message") Message
+          textarea#message.form-control(
+              type="text",
+              rows="6",
+              name="message",
+              autocomplete="off",
+              required
+          )
+
+        button.btn.btn-primary(type="submit", form="sendmail") Send
+
+    .col-md-6
+      :markdown-it
+        Any messages you enter here are directly forwarded to me. I aim to
+        respond within a day.
+
+        Don't be upset about the form, I want to avoid the spam
+        publishing your email address brings with it... And minimize
+        the amount of mail that doesn't reach me, this form is an
+        exception in all my spam filters, you see ;)