💄(email) fix line height email title

The line height of the email title was not
the correct size. We let the title managing
its own line height.

src/mail/mjml/partial/header.mjml

@@ -13,7 +13,7 @@
         <mj-all
             font-family="Roboto, -apple-system, BlinkMacSystemFont, 'Segoe UI', Oxygen, Ubuntu, Cantarell, 'Helvetica Neue', sans-serif"
             font-size="16px"
-            line-height="1.5em"
+            line-height="1.3em"
             color="#3A3A3A"
         />
     </mj-attributes>
@@ -22,6 +22,7 @@
         h1, h2, h3, h4, h5, h6, p {
             margin: 0;
             padding: 0;
+            line-height: normal;
         }
 
         a {
@@ -33,7 +34,6 @@
         h1 {
             color: #161616;
             font-size: 1.4rem;
-            font-weight: 700;
         }
 
         .wrapper {