多Section布局问题：sec3与上方sec-2内容重叠求助

问题现象 #

制作多Section页面布局时，class为sec3的区域与上方的sec-2区域重叠，甚至嵌入到sec-2内的txt类div中；调整区域顺序时显示正常，但在sec-2后添加新区域就出现重叠问题。

问题根源 #

1. HTML标签未正确闭合：sec-2标签内部的<div class="text">和<div class="card">均未闭合，浏览器解析时会将后续的sec3元素错误识别为sec-2的子元素，从而引发重叠嵌入问题。
2. CSS属性值缺失单位：sec-2 .text p.p::before中的bottom: -5未添加单位，导致伪元素布局异常，间接影响整体排版稳定性。

修复步骤 #

• 补全HTML中所有未闭合的标签，确保<sec-2>、<div class="text">、<div class="card">都正确闭合。
• 为CSS中bottom: -5添加单位px，修改为bottom: -5px。

修正后的代码 #

HTML代码 #

<sec-2 class="mmargin">
   <div class="image">
   </div>
   <div class="text">
      <h2>Stay productive, wherever you are</h2>
      <p>
         Lorem ipsum dolor sit amet consectetur adipisicing elit. Temporibus
         doloribus ipsa cum. Sapiente quisquam error magnam odit repellendus
         nihil dolorem quis
      </p>
      <p>
         Lorem ipsum dolor sit amet consectetur adipisicing elit. Temporibus
         doloribus ipsa cum. Sapiente quisquam error magnam odit repellendus
         nihil dolorem quis
      </p>
      <p class="p">
         See how Fylo works 
      </p>
      <div class="card">
         <div class="image1">
         </div>
         <p>
            Lorem, ipsum dolor sit amet consectetur adipisicing elit. Qui omnis ducimus veniam, cupidita
         </p>
         <div class="av">
            <div class="image2">
            </div>
            <div class="txt">
               <h3>
                  Kyle Burton
               </h3>
               <p>
                  Founder &amp; CEO, Huddle
               </p>
            </div>
         </div>
      </div> <!-- 闭合card标签 -->
   </div> <!-- 闭合text标签 -->
</sec-2>
<!-- section 2  -->
<!-- section-3  -->
<div class="sec3 mmargin">
   <div class="text">
      <h2>
         Get early access today
      </h2>
      <p>
         Lorem ipsum dolor sit amet consectetur adipisicing elit. Aliquid sapiente a alias libero labore rerum assumenda cupiditate illum iure adipisci. Veniam vel voluptatem deleniti officia culpa sed, asperiores eveniet fugiat.
      </p>
   </div>
   <form action="">
      <input type="email" placeholder="email@example.com">
      <button>
      Get Started For Free
      </button>
   </form>
</div>

CSS代码 #

* {
  box-sizing: border-box;
}

:root {
  --mobile-width: 375px;
  --light-blue: hsl(224, 93%, 58%);
}

.mmargin {
  margin: 50px auto;
}

body {
  margin: 0;
  padding: 0 ;
  font-family: "Open Sans", sans-serif;
  font-weight: 400;
}

h1,
h2,
h3 {
  font-family: "Raleway", sans-serif;
  font-weight: 700;
}

button:hover {
  opacity: 0.5;
  cursor: pointer;
}

/* sec-2  */
sec-2 {
  width: var(--mobile-width);
  display: flex;
  flex-direction: column;
  
}

sec-2 .image {
  margin-bottom: 50px;
}

sec-2 .image img {
  max-width: 100%;
}

sec-2 .text h2 {
  font-size: 20px;
  text-align: center;
  margin: 30px 0;
}

sec-2 .text p.p {
  margin: 50px auto;
  text-align: center;
}

sec-2 .text p.p {
  color: #3da08f;
  position: relative;
}

sec-2 .text p.p:hover {
  opacity: 0.5;
  cursor: pointer;
}

sec-2 .text p.p::before {
  content: "";
  width: 175px;
  height: 2px;
  background-color: #3da08f;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  bottom: -5px; /* 添加单位px */
}

sec-2 .text p.p img {
  width: 25px;
  vertical-align: middle;
}

sec-2 .text .card {
  display: flex;
  flex-direction: column;
  box-shadow: 0 0 10px rgb(197, 197, 197);
  padding: 20px;
}

sec-2 .text .card .image1 {
  width: 40px;
}

sec-2 .text .card .image1 img {
  width: 50%;
}

sec-2 .text .av {
  display: flex;
  align-items: center;
  gap: 15px;
  margin: 30px 0;
}

sec-2 .text .av .image2 {
  width: 50px;
}

sec-2 .text .av img {
  max-width: 100%;
  border-radius: 50%;
}

sec-2 .text .txt {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

sec-2 .text .txt h3 {
  margin: 0;
}

sec-2 .text .txt p {
  margin: 0;
}

/* sec-2  */

/* .sec3  */
.sec3 {
  width: var(--mobile-width);
  background-color: hsl(238, 22%, 44%);
  display: flex;
  flex-direction: column;
  justify-content: center;
  color: white;
  padding: 50px;
}

.sec3 .text h2 {
  text-align: center;
}

.sec3 .text p {
  text-align: center;
  font-size: 18px;
  line-height: 1.5;
}

.sec3 form {
  margin: 30px auto;
}

.sec3 form input {
  width: 50%;
  margin-bottom: 10px;
  opacity: 0.3;
}

.sec3 form button {
  width: 50%;
  text-align: center;
}
/* .sec3  */

内容的提问来源于stack exchange，提问作者Mohammed Abdullah