Bootstrap 列在小屏幕尺寸（移動設備）中不響應

Question

我有一個使用引導程序構建的頁面。 “服務”部分以 lg 和 md 大小正確顯示，但不能以 sm 或 xs（移動）大小顯示。 我在這里想念什么。 我試過包括 col-sm-12 和 col-xs-12，但是當我將屏幕尺寸縮小到移動設備時，它確實會響應。 任何幫助表示贊賞。 如果你想看看這個網站，這里是鏈接： http://pctechtips.org/apps/itcomp/

<div class="py-4 bg-light" id="prices">
    <div class="container">
      <div class="row">
        <div class="col-md-12">
          <h1 class="text-center">Service Prices</h1>
        </div>
      </div>
      <div class="row">
        <div class="col-md-12">
          <p class="lead text-center">Bellow you can see a brief description of our services and price. These fall into three main category: Desktop Support, System Maintanance, and Network Installation. If you would like to know more details, go to the Service page.</p>
        </div>
      </div>
      <div class="row">
        <div class="col-md-4 p-3">
          <div class="card box-shadow rounded border border-secondary" >
            <img class="card-img-top" src="assets/styleguide/thinkstockphotos-479282847.jpg">
            <div class="card-body">
              <h3 class="text-center">Desktop Support</h3>
              <p class="card-text">We provide online or in person Desktop Support by helping user solve technical issues. We fix computers, laptops: adding memory (RAM), replacing hard drive, data migration, virus removal, slow computer.</p>
              <div class="d-flex justify-content-between align-items-center">
                <a class="btn btn-primary" href="services.html#services">learn more</a>
                <h5 contenteditable="true">60 $ 1hr</h5>
              </div>
            </div>
          </div>
        </div>
        <div class="col-md-4 p-3">
          <div class="card box-shadow border border-secondary rounded">
            <img class="card-img-top" src="assets/styleguide/photo-1506399309177-3b43e99fead2.jpg">
            <div class="card-body">
              <h3 class="text-center">System Administration</h3>
              <p class="card-text">We provide Windows Server and Linux Server administration. This includes checking logs. Schedule regular backups. User administration to make sure user have access to network resources.</p>
              <div class="d-flex justify-content-between align-items-center">
                <a class="btn btn-primary" href="services.html#services">learn more</a>
                <h5 style="">100 $ 1hr</h5>
              </div>
            </div>
          </div>
        </div>
        <div class="col-md-4 p-3">
          <div class="card box-shadow border border-secondary rounded">
            <img class="card-img-top" src="assets/styleguide/photo-1544197150-b99a580bb7a8.jpg">
            <div class="card-body">
              <h3 class="text-center">Network Installation</h3>
              <p class="card-text">Whether is a small or large project we will be able to assist you. We can assist with installation of network devices like router, switches, firewall, modems, wireless access points, network printers, servers.</p>
              <div class="d-flex justify-content-between align-items-center">
                <a class="btn btn-primary" href="services.html#services">learn more</a>
                <h5>150 $ 1hr</h5>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>

Answer 1

當調整大小為移動視圖時，我看到列在您的實時演示中正確堆疊。 如果您仍然沒有看到這一點，您可以將 col-12 添加到您的 class 列列表中，該列表將涵蓋中斷點之前的所有內容。

<div class="col-md-4 col-12 p-3">
//column content
</div>

Answer 2

包括元標記你的頭標記

<meta name="viewport" content="width=device-width, initial-scale=1.0">