diff --git a/html/doc.css b/html/doc.css
index 21e926341..8f832c11d 100644
--- a/html/doc.css
+++ b/html/doc.css
@@ -72,14 +72,14 @@ body {
 	background: var(--panel);
 	border-bottom: 6px solid #000;
 	padding: 1.5rem;
-	/* The rings the 2007 pages carried. The image has the light panel colour baked
-	   into it, so it is dropped rather than inverted in dark mode. */
-	background-image: url(images/bg_rings.gif);
+	/* The rings the 2007 pages carried. Transparent, so it rides on --panel. */
+	background-image: url(images/bg_rings.svg);
 	background-repeat: no-repeat;
 	background-position: top right;
 }
 
 @media (prefers-color-scheme: dark) {
+	/* Rings dropped, not inverted: their lavender is a light-panel tone. */
 	.wrap { background-image: none; }
 
 	/* The wordmark is black on transparent, and all but vanishes on the dark field. */
diff --git a/html/httrack.css b/html/httrack.css
index 4f2c01b4f..238e31f37 100644
--- a/html/httrack.css
+++ b/html/httrack.css
@@ -37,7 +37,7 @@ a:active  { text-decoration: underline; }
 	border-bottom: 6px solid #000;
 	padding: 10px;  padding-top: 20px;
 	line-height: 1.65em;
-	background-image: url(images/bg_rings.gif);
+	background-image: url(images/bg_rings.svg);
 	background-repeat: no-repeat;
 	background-position: top right;
 	}
diff --git a/html/images/bg_rings.gif b/html/images/bg_rings.gif
deleted file mode 100644
index 5dc34d1a5..000000000
Binary files a/html/images/bg_rings.gif and /dev/null differ
diff --git a/html/images/bg_rings.svg b/html/images/bg_rings.svg
new file mode 100644
index 000000000..216957706
--- /dev/null
+++ b/html/images/bg_rings.svg
@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="501" height="456" viewBox="0 0 501 456">
+<title>HTTrack rings</title>
+<!-- Transparent, unlike the GIF this replaces: the panel's own #ccd shows through. -->
+<g fill="#b9b9d0" fill-rule="evenodd">
+<path d="M614.59 346.3A323.36 197.55 21.16 1 0 11.46 112.89A323.36 197.55 21.16 1 0 614.59 346.3 ZM590.57 315.66A262.58 160.99 22.18 1 0 104.26 117.43A262.58 160.99 22.18 1 0 590.57 315.66 Z"/>
+<path d="M578.08 292.16A185.6 113.57 21.23 1 0 232.08 157.73A185.6 113.57 21.23 1 0 578.08 292.16 ZM564.4 274.56A150.77 92.55 22.26 1 0 285.34 160.32A150.77 92.55 22.26 1 0 564.4 274.56 Z"/>
+</g>
+</svg>
diff --git a/html/server/images/bg_rings.gif b/html/server/images/bg_rings.gif
deleted file mode 100644
index 5dc34d1a5..000000000
Binary files a/html/server/images/bg_rings.gif and /dev/null differ
diff --git a/html/server/images/bg_rings.svg b/html/server/images/bg_rings.svg
new file mode 100644
index 000000000..216957706
--- /dev/null
+++ b/html/server/images/bg_rings.svg
@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="501" height="456" viewBox="0 0 501 456">
+<title>HTTrack rings</title>
+<!-- Transparent, unlike the GIF this replaces: the panel's own #ccd shows through. -->
+<g fill="#b9b9d0" fill-rule="evenodd">
+<path d="M614.59 346.3A323.36 197.55 21.16 1 0 11.46 112.89A323.36 197.55 21.16 1 0 614.59 346.3 ZM590.57 315.66A262.58 160.99 22.18 1 0 104.26 117.43A262.58 160.99 22.18 1 0 590.57 315.66 Z"/>
+<path d="M578.08 292.16A185.6 113.57 21.23 1 0 232.08 157.73A185.6 113.57 21.23 1 0 578.08 292.16 ZM564.4 274.56A150.77 92.55 22.26 1 0 285.34 160.32A150.77 92.55 22.26 1 0 564.4 274.56 Z"/>
+</g>
+</svg>
diff --git a/html/server/style.css b/html/server/style.css
index add8240d5..dd43c06d0 100644
--- a/html/server/style.css
+++ b/html/server/style.css
@@ -36,7 +36,7 @@ a:active  { text-decoration: underline; }
 	border-bottom: 6px solid #000;
 	padding: 10px;  padding-top: 20px;
 	line-height: 1.65em;
-	background-image: url(images/bg_rings.gif);
+	background-image: url(images/bg_rings.svg);
 	background-repeat: no-repeat;
 	background-position: top right;
 	}
diff --git a/tests/142_webhttrack-content-type.test b/tests/142_webhttrack-content-type.test
index 87013f8fe..00b544ac3 100644
--- a/tests/142_webhttrack-content-type.test
+++ b/tests/142_webhttrack-content-type.test
@@ -24,7 +24,7 @@ python=$(find_python) || {
 
 # The GUI assets asserted below have to exist, or every check goes vacuous.
 for asset in server/ping.js server/style.css images/screenshot_01.jpg \
-    images/bg_rings.gif img/guide-droid-opt-spider.png \
+    images/bg_rings.svg images/header_title_4.gif img/guide-droid-opt-spider.png \
     server/div/com.httrack.WebHTTrack.metainfo.xml; do
     test -f "${distdir}/html/${asset}" || fail "missing GUI asset ${asset}"
 done
@@ -131,7 +131,8 @@ def check_html_headers(path):
 check_html_headers("/server/index.html")
 check_type("/server/ping.js", "text/javascript")
 check_type("/server/style.css", "text/css")
-check_type("/images/bg_rings.gif", "image/gif")
+check_type("/images/bg_rings.svg", "image/svg+xml")
+check_type("/images/header_title_4.gif", "image/gif")
 check_type("/img/guide-droid-opt-spider.png", "image/png")
 check_type("/images/screenshot_01.jpg", "image/jpeg")
 # Dots in the stem: the type comes from the last one, not the first.