diff --git a/doc/manual/custom.css b/doc/manual/custom.css
index b90f5423f..9e8e3886f 100644
--- a/doc/manual/custom.css
+++ b/doc/manual/custom.css
@@ -1,3 +1,25 @@
+:root {
+    --sidebar-width: 23em;
+}
+
+h1.menu-title::before {
+  content: "";
+  background-image: url("./favicon.svg");
+  padding: 1.25em;
+  background-position: center center;
+  background-size: 2em;
+  background-repeat: no-repeat;
+}
+
+
+h1.menu-title {
+  padding: 0.5em;
+}
+
+.sidebar .sidebar-scrollbox {
+  padding: 1em;
+}
+
 h1:not(:first-of-type) {
     margin-top: 1.3em;
 }
diff --git a/doc/manual/local.mk b/doc/manual/local.mk
index 698a9289b..71ad5c8e6 100644
--- a/doc/manual/local.mk
+++ b/doc/manual/local.mk
@@ -217,7 +217,7 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
 # `@docroot@` is to be preserved for documenting the mechanism
 # FIXME: maybe contributing guides should live right next to the code
 # instead of in the manual
-$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/store/types $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md $(d)/src/release-notes/rl-next.md
+$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/store/types $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md $(d)/src/release-notes/rl-next.md $(d)/src/figures $(d)/src/favicon.png $(d)/src/favicon.svg
 	$(trace-gen) \
 		tmp="$$(mktemp -d)"; \
 		cp -r doc/manual "$$tmp"; \
diff --git a/doc/manual/src/favicon.png b/doc/manual/src/favicon.png
new file mode 100644
index 000000000..1ed2b5fe0
Binary files /dev/null and b/doc/manual/src/favicon.png differ
diff --git a/doc/manual/src/favicon.svg b/doc/manual/src/favicon.svg
new file mode 100644
index 000000000..1d2a6e835
--- /dev/null
+++ b/doc/manual/src/favicon.svg
@@ -0,0 +1 @@
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\ No newline at end of file