diff --git a/css/themes/common.css b/css/themes/common.css
new file mode 100644
index 0000000..540d72f
--- /dev/null
+++ b/css/themes/common.css
@@ -0,0 +1,7 @@
+:is(h1,h2,h3,h4,h5,h6) > a.header-anchor {
+ opacity: 0
+}
+
+:is(h1,h2,h3,h4,h5,h6):hover > a.header-anchor {
+ opacity: 1
+}
diff --git a/index.html b/index.html
index 0d2fc85..63c0fa0 100644
--- a/index.html
+++ b/index.html
@@ -9,6 +9,7 @@
+