CSS类订单显示不同的结果

amd*_*kfe 2 html css css3

bb班的背景颜色将是红色的,如果我之前移动代码intro-block类的CSS代码,但是如果我把它放在后intro-block颜色不改变,并没有任何反应类的CSS代码!谁能告诉我为什么会这样?!

.left-column {
  width: 35%;
  margin-left: 20px;
  margin-right: 50px;
  float: left;
  overflow: hidden;
}

.right-column {
  overflow: hidden;
}

.intro-block {
  background-color: #22AAA1;
  margin: 0 auto;
  /*max-width: 950px;*/}
}

.bb {
  background-color: red;
}
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<body>
  <header>
    <section class="intro-block">
      <div class="left-column">
        <img class="profile-pic right-column" src="img/11.jpg">
      </div>
      <div class="right-column">
        <h1>lorem ipsum</h1>
        <p>
          <h4>lorem ipsum</h4>
        </p>
      </div>
    </section>
  </header>
  <main>
    <section class="bb">
      <h3>lorem ipsum</h3>
      <div class="left-column">
        <div>
          <p>lorem ipsum</p>
        </div>
      </div>
      <div class="right-column">
        <h5>lorem ipsum</h5>
      </div>
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dip*_*pas 5

}之前有一个额外的.bb {}

注意:不要包含标题(h1h6)p

您应该缩进/整理代码以便更好地阅读,并且您可以轻松地发现这些错误

.left-column {
  width: 35%;
  margin-left: 20px;
  margin-right: 50px;
  float: left;
  overflow: hidden;
}

.right-column {
  overflow: hidden;
}

.intro-block {
  background-color: #22AAA1;
  margin: 0 auto;
  /*max-width: 950px;*/
}


.bb {
  background-color: red;
}
Run Code Online (Sandbox Code Playgroud)
<body>
  <header>
    <section class="intro-block">
      <div class="left-column">
        <img class="profile-pic right-column" src="img/11.jpg">
      </div>
      <div class="right-column">
        <h1>lorem ipsum</h1>
        <h4>lorem ipsum</h4>
      </div>
    </section>
  </header>
  <main>
    <section class="bb">
      <h3>lorem ipsum</h3>
      <div class="left-column">
        <div>
          <p>lorem ipsum</p>
        </div>
      </div>
      <div class="right-column">
        <h5>lorem ipsum</h5>
      </div>
      </section>
  </main>
Run Code Online (Sandbox Code Playgroud)