html:
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>test</title>
<link rel="stylesheet" href="order.css"></head>
<body>
<p class="nav">
<h1>Plateform</h1>
<ul>
<li>
<p>Order</p>
<p id="selected"></p>
</li>
<li>
<p>Menu</p>
</li>
<li>
<p>Restuarant</p>
</li>
</ul>
</p>
<p class="content">
<p id="left">
<ul class="rtab">
<li>
<p>Manage order</p>
</li>
<li>
<p>Completed order</p>
</li>
<li>
<p>Closed order</p>
</li>
</ul>
</p>
<p id="right">
<input id="search" type="text" >
<button id="search-button" >Search</button>
<p class="oders">
<ul class="ctab">
<li>All</li>
<li>Accepted</li>
<li>Failed</li>
</ul>
<p class="allorders">
<p class="order1">
<p class="title">dsdsd</p>
<p class="userinfo">dsdsd</p>
<p calss="lastt">dsdsdsds</p>
</p>
</p>
</p>
</p>
</p></body>
css:* {
font-family: Arial;
margin: 0 0;}
body {
background: #333333;}
.html {
font-size: 6px;
h1: 2rem;}
.nav {
height: 3rem;
background-color: #000000;
padding-top: 1rem;}
.nav>h1 {
color: #ffffff;
margin-left: 3rem;
display: inline-block;}
.nav>ul {
position: absolute;
top: 1.4rem;
left: 20rem;
display: flex;
flex-flow: row-wrap;
list-style: none;
color: aliceblue;
width: 50rem;
flex-pack: justify;
justify-content: space-around;}
position: relative;
top: 0.3rem;
background-color: #F5B23D;
height: 0.5rem;}
.nav>ul>li {
font-size: 1.5rem;
width: 12rem;
justify-content: space-around;
text-align: center;}
.nav>ul>li>p {
margin: auto;}
.content {
display: flex;
flex-direction: row;
justify-content: space-between;
width: auto;
margin: 0;
padding: 1rem;
background-color: #333333;}
.content p {
margin-top: 0.5rem;
width: auto;
height: 50rem;}
background-color: #1F1F1F;
margin-right: 1.5rem;
margin-left: 1rem;}
flex-grow: 16;}
.rtab {
display: block;
text-align: center;
height: 30rem;
width: 10rem;
padding-top: 2rem;}
.rtab>li {
line-height: 3rem;
list-style: none;
font-size: 1rem;
font-weight: bolder;
height: 3rem;
width: 10.5rem;
margin-left: -1.5rem;
margin-bottom: 2rem;
color: #acacac;}
.rtab>li:first-child {
background-color: #333333;
color: #ffffff;}
width: 36rem;
height: 2.5rem;}
width: 10rem;
margin-left: 1rem;
height: 2.5rem;
background-color: #65b59a;
color: aliceblue;
}.oders{
background-color: #333333;
margin-top: 2rem;}
.ctab{
margin-top: 1.5rem;
background-color: #000000;
color: aliceblue;
list-style: none;
height: 3.5rem;
margin-bottom: -0.5rem;}
.ctab>li{
display: inline-block;
margin-right: 2rem;
width: 8rem;
text-align: center;
font-weight: 800;
height: 3rem;
line-height: 3rem; }
.ctab>li:first-child{
border-bottom: 0.5rem solid;}
.allorders{
position: relative;
background-color: #c1c1c1;
padding-top: 0.5rem;
height: 10px;
width: 10px;}
.order1{
background-color: aliceblue;
height: 1px;
margin: 1rem;
margin-top: 1rem;
}.title{
height: 1rem;
background-color: bisque;
height: 1rem;}
.userinfo{
height: 1rem;
background-color: aqua;}
.lastt{
height: 1rem;
background-color: #161617;}
你的高度是1px
在想要的p里面加上css内联样式表就好了，比如
百度一下css获得更多
PS:这格式真难受= =||