div 元素在 CSS 之后不显示

Question

Web开发的新手，我正在创建一个新网站，目前使用html，js和css，但是应用css后缺少一些元素？ 两个div 元素 box1 和 box2 都丢失了，其中包含所有内容。我在 chrome 中打开了检查选项，看到它们在代码中但没有加载？

<header>
<img src="SAGE LOGO.png">
<nav>
<ul>
<li><a href="#">Home</a></li>
<li><a href="#">Help</a></li>
</ul>
</nav>
</header>
<main>
<div class="box1">
<label class="ld-label">
Project Number:
</label>
<input class="ld-url-input" type="text" id="fetchURL" />
<button type="button" id="add" class="design_button add">Draw</button>
</div>
<div class="box2">
<form method="post" action="data.php">
<label class="ld-label">
Add Project:
</label>
<input class="ld-url-input" type="text" name="textdata">
<input type="submit" name="submit" value="Submit">
</form>
</div>
</main>
<div id="super">
<div id="container">
</div>
</div>

.CSS：

header img {
height: 80px;
}
body {
height: 125vh;
background-color: #222641;
background-size: cover;
font-family: sans-serif;
}
main {
color: white;
}
header {
background-color: #A80B16;
position: fixed;
top: 0;
left: 0;
right: 0;
height: 80px;
}
.ld-label {
width: 200px;
}
.ld-url-input {
display: inline-block;
}

Answer 1

您的header与您的内容重叠。

删除position: fixed;header或为您的main提供padding-top: 80px;

header img {
height: 80px;
}
body {
background-color: #222641;
background-size: cover;
font-family: sans-serif;
}
main {
color: white;
padding-top: 80px;
}
header {
background-color: #A80B16;
position: fixed;
top: 0;
left: 0;
right: 0;
height: 80px;
}
.ld-label {
width: 200px;
}
.ld-url-input {
display: inline-block;
}

<header>
<img src="SAGE LOGO.png">
<nav>
<ul>
<li><a href="#">Home</a></li>
<li><a href="#">Help</a></li>
</ul>
</nav>
</header>
<main>
<div class="box1">
<label class="ld-label">
Project Number:
</label>
<input class="ld-url-input" type="text" id="fetchURL" />
<button type="button" id="add" class="design_button add">Draw</button>
</div>
<div class="box2">
<form method="post" action="data.php">
<label class="ld-label">
Add Project:
</label>
<input class="ld-url-input" type="text" name="textdata">
<input type="submit" name="submit" value="Submit">
</form>
</div>
</main>
<div id="super">
<div id="container">
</div>
</div>
<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/data.js"></script>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="./script.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>

Answer 2

由于标题框1和box2的固定位置移动到标题后面，因为固定位置划分不会占用它的空间，所以要解决它，请在主元素中放入css下方。

main{
margin-top: 82px;
padding: 20px;
}