add CSS

calc.html

@@ -2,9 +2,7 @@
 <html>
     <head>
        <title>HTML / CSS</title>
-        <style>
+        <link rel="stylesheet" type="text/css" href="styles.css">
-
-        </style>
     </head>
     <body>
         <form method="GET" action="http://webex.sdi.hevs.ch/calc">

styles.css

@@ -0,0 +1,15 @@
+body {
+    background-color: lightgreen;
+}
+
+input[type="number"] {
+    background-color: yellow;
+}
+
+input[type="submit"] {
+    background-color: deepskyblue;
+}
+
+input[type="reset"] {
+    background-color: palevioletred;
+}