Add a CipherCell header to every page but the cover

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

report_generator/template/report.css

@@ -62,6 +62,13 @@
     size: A4;
     margin: 22mm 18mm 18mm 18mm;
 
+    @top-center {
+        content: element(page-header);
+        width: 100%;
+        vertical-align: bottom;
+        padding-bottom: 4mm;
+    }
+
     @bottom-left {
         content: string(scan-footer);
         font-family: "Space Grotesk", sans-serif;
@@ -101,6 +108,26 @@ code,
     font-size: 0.93em;
 }
 
+/* The cover carries the mark large already; a second, small one above it would only repeat it. */
+@page :first {
+    @top-center {
+        content: none;
+    }
+}
+
+/* The mark -- the logo and the company name, which the image carries together -- above every page,
+   ruled off from the content. */
+.page-header {
+    position: running(page-header);
+    padding-bottom: 1.6mm;
+    border-bottom: 0.4pt solid var(--border);
+}
+
+.page-header img {
+    height: 5mm;
+    display: block;
+}
+
 /* Carried into the running footer on every page. Set once, on the cover. */
 .footer-scan {
     string-set: scan-footer content();