diff --git a/docs/index.html b/docs/index.html
index 89ce22a..5ae1f09 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -59,7 +59,15 @@ <h1>@ecodev/natural-layout</h1>
 
         <h1 id="section-start">Getting started</h1>
 
-        <p>Available breakpoints prefixes : <strong>xs, sm, md, lg, xl</strong>.</p>
+        <p>
+            Available breakpoints prefixes : <strong>sm</strong>, <strong>md</strong>, <strong>lg</strong>,
+            <strong>xl</strong>.
+        </p>
+        <p>
+            <strong>xs</strong> does not exist because it is the default breakpoint. We design for
+            <strong>xs</strong> first, with <code>nat-vertical</code>, then adapt for other breakpoints if needed, with
+            <code>nat-md-horizontal</code>.
+        </p>
 
         <p><strong>Usage : </strong> <span class="docs-class">class="nat[-breakpoint]-class[-size]"</span></p>