Web: Extract base template.

Change-Id: I20a4fbb04aa75a94f96617b0c4d1be00ab3e4aca
diff --git a/src/main/resources/templates/base.html b/src/main/resources/templates/base.html
new file mode 100644
index 0000000..8fefe31
--- /dev/null
+++ b/src/main/resources/templates/base.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="UTF-8">
+
+  <title>{#insert title}{/}</title>
+
+  <link rel="stylesheet" type="text/css" href="/common.css" />
+  <script type="module" src="/components.js"></script>
+</head>
+
+<body>
+{#insert body}{/}
+</body>
+</html>