PCのCSSが効かない

サイト作成の勉強中です。
CSSでボタン（input submit）の大きさを大きくしたのですが、PCでは大きくなりません。
スマホで見ると大きくなっています。
なぜでしょうか？

index.php
1<?php
2
3ini_set('display_errors', 1 );
4error_reporting(E_ALL);
5
6define('DSN', 'mysql:host=127.0.0.1;dbname=drh;charset=utf8mb4');
7define('DB_USER', 'root');
8define('DB_PASS', 'a61CXdhaSCKt');
9
10try {
11  $pdo = new PDO(
12    DSN,
13    DB_USER,
14    DB_PASS,
15    [
16      PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
17      PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_OBJ,
18      PDO::ATTR_EMULATE_PREPARES => false,
19    ]
20  );
21} catch (PDOException $e) {
22  echo $e->getMessage();
23  exit;
24}
25
26function h($str) {
27  return htmlspecialchars($str, ENT_QUOTES, 'UTF-8');
28}
29
30function saveBundle($pdo) {
31  $f2a4 = filter_input(INPUT_POST, 'f2a4');
32  $f2a3 = filter_input(INPUT_POST, 'f2a3');
33  $f2b5 = filter_input(INPUT_POST, 'f2b5');
34  $f2b4 = filter_input(INPUT_POST, 'f2b4');
35  $f3a4 = filter_input(INPUT_POST, 'f3a4');
36  $f3a3 = filter_input(INPUT_POST, 'f3a3');
37  $f3b5 = filter_input(INPUT_POST, 'f3b5');
38  $f3b4 = filter_input(INPUT_POST, 'f3b4');
39  $stmt = $pdo->prepare("update bundle set 
40                            f2a4 = :f2a4,
41                            f2a3 = :f2a3,
42                            f2b5 = :f2b5,
43                            f2b4 = :f2b4, 
44                            f3a4 = :f3a4,
45                            f3a3 = :f3a3,
46                            f3b5 = :f3b5,
47                            f3b4 = :f3b4"
48                        );
49  $stmt->bindValue('f2a4', $f2a4, PDO::PARAM_INT);
50  $stmt->bindValue('f2a3', $f2a3, PDO::PARAM_INT);
51  $stmt->bindValue('f2b5', $f2b5, PDO::PARAM_INT);
52  $stmt->bindValue('f2b4', $f2b4, PDO::PARAM_INT);
53  $stmt->bindValue('f3a4', $f3a4, PDO::PARAM_INT);
54  $stmt->bindValue('f3a3', $f3a3, PDO::PARAM_INT);
55  $stmt->bindValue('f3b5', $f3b5, PDO::PARAM_INT);
56  $stmt->bindValue('f3b4', $f3b4, PDO::PARAM_INT);
57  $stmt->execute();
58}
59
60function doneBundle($pdo) {
61  $stmt = "update bundle set 
62            f2a4 = 0,
63            f2a3 = 0,
64            f2b5 = 0,
65            f2b4 = 0, 
66            f3a4 = 0,
67            f3a3 = 0,
68            f3b5 = 0,
69            f3b4 = 0";
70  $pdo -> query($stmt);
71}
72
73function getBundle($pdo) {
74  $stmt = $pdo->query("select * from bundle");
75  $bundle = $stmt->fetch();
76  return $bundle;
77}
78
79if ($_SERVER['REQUEST_METHOD'] === 'POST') {
80
81  $action = filter_input(INPUT_GET, 'action');
82
83  switch ($action) {
84    case 'save':
85      saveBundle($pdo);
86      break;
87    case 'done':
88      doneBundle($pdo);
89      break;
90  }
91}
92
93$bundle = getBundle($pdo);
94
95?>
96<!DOCTYPE html>
97<html lang="ja">
98<head>
99    <meta charset="UTF-8">
100    <meta http-equiv="X-UA-Compatible" content="IE=edge">
101    <meta name="viewport" content="width=device-width, initial-scale=1.0">
102    <title>Tools</title>
103    <meta http-equiv="Content-Style-Type" content="text/css">
104    <link rel="stylesheet" href="css/styles.css">
105</head>
106<body>
107<div class="doc">
108    <form>
109      <h1>2F 食堂</h1>
110      <ul>
111          <li><label for="f2a4">A4</label><input class="bundle" type="number" name="f2a4" value=<?= $bundle->f2a4; ?>></li>
112          <li><label for="f2a3">A3</label><input class="bundle" type="number" name="f2a3" value=<?= $bundle->f2a3; ?>></li>
113          <li><label for="f2b5">B5</label><input class="bundle" type="number" name="f2b5" value=<?= $bundle->f2b5; ?>></li>
114          <li><label for="f2b4">B4</label><input class="bundle" type="number" name="f2b4" value=<?= $bundle->f2b4; ?>></li>
115      </ul>
116      <h1>3F 会議室</h1>
117      <ul>
118          <li><label for="f3a4">A4</label><input class="bundle" type="number" name="f3a4" value=<?= $bundle->f3a4; ?>></li>
119          <li><label for="f3a3">A3</label><input class="bundle" type="number" name="f3a3" value=<?= $bundle->f3a3; ?>></li>
120          <li><label for="f3b5">B5</label><input class="bundle" type="number" name="f3b5" value=<?= $bundle->f3b5; ?>></li>
121          <li><label for="f3b4">B4</label><input class="bundle" type="number" name="f3b4" value=<?= $bundle->f3b4; ?>></li>
122      </ul>
123      <input type="submit" value="Save" formaction="?action=save" formmethod="POST" class="button"/>
124      <input type="submit" value="Done" formaction="?action=done" formmethod="POST" class="button"/>
125  </form>
126</div>
127</body>
128</html>

styles.css
1h1 {
2    font-size: 24px;
3    margin: 0;
4}
5ul {
6    margin: 0;
7    padding: 0;
8    margin: 0px 0px 8px;
9}
10li {
11    font-size: 16px;
12    list-style: none;
13}
14.bundle {
15    width: 100px;
16    font-size: 16px;
17    text-align: right;
18    margin-left: 24px;
19}
20.button {
21  height: 50px;
22  width: 100px;
23}