tip.html
1    <!DOCTYPE html>
2    <html>
3    <head>
4      <meta charset="utf-8">
5      <meta name="viewport" content="width=device-width">
6      <title>Tip Calculator</title>
7      <link href="tip.css" rel="stylesheet" type="text/css" />
8    </head>
9    <body>
10   <select id="service">
11     <option value="15">Please rate your service.</option>
12     <option value="20">Amazing!</option>
13     <option value="17">Really good</option>
14     <option value="15">Nothing special</option>
15     <option value="12">Could have been better</option>
16     <option value="10">It was pretty bad</option>
17   </select>
18   
19   <div id="explanation"></div>
20   <input id="input">
21   <button id="button">Calculate</button>
22   <div id="output"></div>
23   <script src="tip.js"></script>
24   </body>
25   </html>
26