diff --git a/docs/iris/src/_static/style.css b/docs/iris/src/_static/style.css
index dc4dd1bb9a..a350025909 100644
--- a/docs/iris/src/_static/style.css
+++ b/docs/iris/src/_static/style.css
@@ -50,6 +50,15 @@ p.hr_p:after {
     width: calc(100% - 110px - 2em - 4%);
 }
 
+.strapline p {
+    font-size: medium;
+    font-family: 'Alike', serif;
+    font-weight: bold;
+    color: #444444;
+    max-width: 52ch;
+    margin-top: 0.25em;
+}
+
 .header-content h1 {
     font-size: 3.5rem;
     font-family: 'Alike', serif;
diff --git a/docs/iris/src/_templates/layout.html b/docs/iris/src/_templates/layout.html
index 26082f9fe7..fce6b98045 100644
--- a/docs/iris/src/_templates/layout.html
+++ b/docs/iris/src/_templates/layout.html
@@ -39,10 +39,10 @@
       <h1>
           Iris <span class="version">v2.1</span>
       </h1>
-      <h2>
-         a powerful, format-agnostic, and community-driven Python library for analysing and
-         visualising Earth science data
-      </h2>
+      <p>
+         A powerful, format-agnostic, and community-driven Python library for analysing and
+         visualising Earth science data.
+      </p>
     </div>
 </div>