早上好，大家好，我正在做一个EPQ项目，帮助上瘾的人，并遇到一些问题，

我似乎无法在我的 table 上启用边框，我猜它的东西很小就像丢失了;或者甚至只是一个拼错标签，在我提交物品之前我已经没有时间了，似乎无法解决它的生命，所以，不幸的是，我不得不寻求帮助:)

我已经发布了完整的CSS脚本以及此处的表格

html {
      
    font: normal 20px Calibri, Tahoma;
    margin: 0px;
    padding: 0px;
} 

body { 

    margin: 100 0;
    position: absolute;
    top: 100px;
    height: 100px;
}

.header {
    padding: 0px;
    margin: 0 0px;
    text-align: center;
    background: #1abc9c;
    color: Black;
    font-size: 40px;
    border-style: solid;
    border-width: 1px;
    border-color: black;
    position: fixed;
    left: 0px;
    top: 45px;
    width: 100%;
    height: 50px;
} 

h1 {
    text-align: center;
    colour: black;
    font-size: 30px;
    padding: 10px;        
}

h2 {
    text-align:left;
    colour: black;
    font-size:20px;
    text-decoration-line: underline;
}

h3 {
    text-align:center;
    colour: black;
    font-size:40px;                
}

h4 {
    text-align: left;
    colour: black;
    font-size: 15px;
    padding: 0px;
    text-decoration-style: solid;
    text-align: left;
}

h5 {
    text-align: left;
    colour: black;
    font-size: 60px;
    padding: 0px;        
}

p {
    font-family: Tahoma;
    text-align: left;
    color:black;
    font-size:13px;        
}

.hidden {display: none;}

.unhidden { display: block; }

/* The navigation bar */
.navbar {
    overflow: hidden;
    background-color: #258422;
    position: fixed; /* Set the navbar to fixed position */
    top: 0; /* Position the navbar at the top of the page */
    left: 0px;
    width: 100%; /* Full width */
    font-size: 15px;                
}

/* Links inside the navbar */
.navbar a {
    float: left;
    display: block;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 10px;
    text-decoration: none;        
}

/* Change background on mouse-over */
.navbar a:hover {
    background: #2c9128;
    color: white;
}

/* Main content */
.main {
    margin-top: 30px; /* Add a top margin to avoid content overlay */
    
}
/* Header of website */

.header {
    background-color: #F1F1F1;
    text-align: center;
    padding: 0px;        
}    

/* Website footer */
.footer {
    background-color: #00000;
    text-align: center;
    padding: 10px;
}

/* Website Buttons */
.button {
    background-color: #258422; /* Green */
    border-radius: 0px;
    border: 1px solid #555555;
    color: white;
    padding: 10px 24px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 15px;
    width: 250px;        
}

/* Hover config */

.button:hover {
    -webkit-transition-duration: 0.4s; /* Safari */
    transition-duration: 0.3s;
    background-color: #2c9128;
    color: white;
}

/* drop down styles */

button, .flip {
  font-size: 15px;
  padding: 10px;
  text-align: left;
  background-color: #d3e4ff;
  color: black;
  border: solid 2px #4CAF50;
  width: 50%;
  
.table {
    background-color: #555555;
    width: 10px;
    border: 1px solid #555555;
}

/* defines center tag */
.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: auto;
    text-align: center;
}

<!DOCTYPE html>
<hmtl>

<head>
<meta charset="utf-8">
<link rel="stylesheet" href="./css/styles.css">

<div class="header">
  <b>This is the checklist for the information included on the website</b>
</div> 

<div class="navbar">
<a href="index.html">Home</a>
<a href="checklists.html">Back</a>
  </div>

</head>

<body>

<table>
<table style="width:100%">
<th><h2 align="center">Task</h2></th>
<th><h2 align="center">Info</h2></th>
<th><h2 align="center">Completed</h2></th>
<th><h2 align="center"> Date Started</h2></th>
<th><h2 align="center"> Date of completion</h2></th>
</tr>
<tr>
<td>1) Researched Different types of addiction and looked into different definitions</td>
<td><div title="sample text"><img src="./images/info.png" width="50" height="50" class="center"></div></td>
<td><center><img src="./images/cross.png" alt="cross" width="50" height="50"></center></td>
<td><center>5th December 2018</center></td>
<td><center>N/A</center></td>
</tr>
<tr>
<td>2) Input rough data under Definition / Alcohol</td>
<td><div title="Sample text"><img src="./images/info.png" width="50" height="50" class="center"></div></td>
<td><center><img src="./images/cross.png" alt="cross" width="50" height="50"></center></td>
<td><center>7th December 2018</center></td>
<td><center>N/A</center></td>
</tr> 
<tr>
<td>3) Input rough data under Definition / Drugs</td>
<td><div title="Sample text"><img src="./images/info.png" width="50" height="50" class="center"></div></td>
<td><center><img src="./images/cross.png" alt="cross" width="50" height="50"></center></td>
<td><center>7th December 2018</center></td>
<td><center>N/A</center></td>
</tr> 
</table>

</body>
</html>

如果你发现任何其他看起来不正确的东西我会非常感谢反馈非常感谢:)

css table