diff --git a/index.html b/index.html
index 4ead059..bbaeaff 100644
--- a/index.html
+++ b/index.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html>
+<html lang="en">
 	<head>
 		<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
 		<title>KV diagram calculator</title>
@@ -27,9 +27,14 @@
 				width: 100%;
 				text-align: center;
 			}
+			h1 {
+				display: inline-block;
+				padding-right: 10px;
+			}
 		</style>
 	</head>
 	<body>
+		<div><h1>KV diagram calculator</h1><a href="https://git.scc.kit.edu/uskyk/kv">(source code)</a></div>
 		<div id="main">
 			<div id="settings">
 				<label>Number of variables: <input type="number" min="1" value="3" id="variables"></label><button id="apply-variables">Apply</button>
@@ -46,7 +51,7 @@
     			<option value="dmf">DMF</option>
     			<option value="kmf">KMF</option>
 			</select></label>
-			<label><input type="checkbox" id="labels">Print variable labels</label></div>
+			<label><input type="checkbox" id="labels" checked>Print variable labels</label></div>
 			<button id="calculate">Run</button>
 			<div id="output-help"></div>
 			<div id="output-container"></div>
