Add subtle sponsor line: header strip + footer, tracked UTM

css/site.css

@@ -871,3 +871,36 @@ html.js [data-rv].rv-in { opacity: 1; transform: none; }
   font-size: var(--step-sm);
   color: var(--muted);
 }
+
+/* ---------- sponsor line: one quiet line under the masthead, one in the footer ---------- */
+.sponsor { border-bottom: 1px solid var(--rule); }
+.sponsor p {
+  max-width: var(--max);
+  margin: 0 auto;
+  padding: 7px var(--pad) 8px;
+  display: flex;
+  flex-wrap: wrap;
+  align-items: baseline;
+  gap: 8px;
+  font-size: var(--step-sm);
+  color: var(--muted);
+}
+.sponsor-label {
+  font-size: var(--step-xs);
+  letter-spacing: 0.14em;
+  text-transform: uppercase;
+  font-weight: 600;
+  color: var(--oak);
+}
+.sponsor a {
+  color: var(--ink);
+  text-decoration-color: var(--oak);
+  text-underline-offset: 3px;
+}
+.sponsor-note { opacity: 0.72; }
+.sponsor-foot {
+  margin: 10px 0 0;
+  font-size: var(--step-sm);
+  color: var(--muted);
+}
+.sponsor-foot .sponsor-label { margin-right: 6px; }

index.html

@@ -34,6 +34,12 @@
   <a class="nav-cta" href="#ask">Ask a question</a>
 </header>
 
+<aside class="sponsor" aria-label="Hosting sponsor">
+  <p><span class="sponsor-label">Help us</span>
+     <a href="https://ODOO4projects.com/?utm_source=oc-guy.com&amp;utm_medium=website&amp;utm_campaign=homepage" target="_blank" rel="noopener sponsored">Odoo Community hosting</a>
+     <span class="sponsor-note">— our hosting sponsor</span></p>
+</aside>
+
 <main id="top">
 
   <section class="lead" id="welcome" aria-labelledby="lead-title">
@@ -194,6 +200,8 @@
   <div class="foot-cols">
     <p class="foot-note">Odoo Community advocate. Written by Oliver Arnold, 安雷威 —
       no partner programme, no licences sold.</p>
+    <p class="sponsor-foot"><span class="sponsor-label">Help us</span>
+      <a href="https://ODOO4projects.com/?utm_source=oc-guy.com&amp;utm_medium=website&amp;utm_campaign=homepage" target="_blank" rel="noopener sponsored">Odoo Community hosting</a> — our hosting sponsor</p>
     <nav class="foot-links" aria-label="Elsewhere">
       <a href="https://www.odoo.com/documentation" target="_blank" rel="noopener">Documentation</a>
       <a href="https://github.com/OCA" target="_blank" rel="noopener">OCA modules</a>