CSS不适用于提交按钮

Question

我在我的html网站上使用了css文件。起初它工作正常。我添加了导航栏的CSS，它工作。但现在我的页面中有一个提交按钮。我为此添加了css。但没有任何反应。请帮忙。

table,
th,
td {
  border: 1.5px solid black;
}

table {
  border-collapse: collapse;
}

table {
  width: 100%;
}

th {
  height: 50px;
}

th {
  text-align: center;
}

td {
  height: 50px;
  vertical-align: bottom;
}

th,
td {
  padding: 15px;
  text-align: left;
}

tr:nth-child(even) {
  background-color: #f2f2f2
}

thead tr {
  background-color: #4CAF50;
  color: white;
}


/* Add a black background color to the top navigation */

.topnav {
  background-color: #0099cc;
  overflow: hidden;
}


/* Style the links inside the navigation bar */

.topnav a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}


/* Change the color of links on hover */

.topnav a:hover {
  background-color: #ddd;
  color: black;
}


/* Add a color to the active/current link */

.topnav a.active {
  background-color: #4CAF50;
  color: white;
}

body {
  /*background-image: url("images/ll.jpg");        
          background-repeat: no-repeat;
          background-size:cover;*/
  background-color: white;
}

input[type="submit"] {
  padding: 5px 15px;
  background: #0099cc;
  border: 0 none;
  cursor: pointer;
  -webkit-border-radius: 5px;
  border-radius: 5px;
}

<form>
  <center>
  <input type="submit" name="btnbookparty" value="Book a Party"/>
  </center>
</form>