title: Only first item in bootstrap accordion is collapsing - z-index problem
body: <p>Only the first item in my accordion is working.... I haven't touched the HTML code yes, only the css for now... 
  I used the working example in bootstrap website but as soon as I styled it, it got messed up...</p>
  
  <p>the problem is the Z-INDEX. When I tried it without using z-index, it worked great. The problem is I need the z-index in order to hide each top of an element behind the bottom rounded border of the element before it.</p>
  
  <p>Is there a way to do what I need without using the z-index property?</p>
  
  <pre><code>&lt;div class="accordion" id="accordionExample"&gt;
    &lt;div class="card" id="historyCard"&gt;
      &lt;div class="card-header" id="headingOne"&gt;
        &lt;h5 class="mb-0"&gt;
          &lt;button class="btn btn-link" type="button" data-toggle="collapse" data-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne"&gt;
                                                  היסטוריה
                                              &lt;/button&gt;
        &lt;/h5&gt;
      &lt;/div&gt;
  
      &lt;div id="collapseOne" class="collapse show" aria-labelledby="headingOne" data-parent="#accordionExample"&gt;
        &lt;div class="card-body"&gt;
          Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird
          on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table,
          raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="card" id="whoWeAreCard"&gt;
      &lt;div class="card-header" id="headingTwo"&gt;
        &lt;h5 class="mb-0"&gt;
          &lt;button class="btn btn-link collapsed" type="button" data-toggle="collapse" data-target="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"&gt;
                                                  מי אנחנו?
                                              &lt;/button&gt;
        &lt;/h5&gt;
      &lt;/div&gt;
      &lt;div id="collapseTwo" class="collapse" aria-labelledby="headingTwo" data-parent="#accordionExample"&gt;
        &lt;div class="card-body"&gt;
          Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird
          on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table,
          raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="card" id="numbersCard"&gt;
      &lt;div class="card-header" id="headingThree"&gt;
        &lt;h5 class="mb-0"&gt;
          &lt;button class="btn btn-link collapsed" type="button" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree"&gt;
                                                  "בשבילי" במספרים"
                                              &lt;/button&gt;
        &lt;/h5&gt;
      &lt;/div&gt;
      &lt;div id="collapseThree" class="collapse" aria-labelledby="headingThree" data-parent="#accordionExample"&gt;
        &lt;div class="card-body"&gt;
          Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird
          on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table,
          raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="card" id="sayingCard"&gt;
      &lt;div class="card-header" id="headingThree"&gt;
        &lt;h5 class="mb-0"&gt;
          &lt;button class="btn btn-link collapsed" type="button" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree"&gt;
                                                  צעירים אומרים...
                                              &lt;/button&gt;
        &lt;/h5&gt;
      &lt;/div&gt;
      &lt;div id="collapseFour" class="collapse" aria-labelledby="headingThree" data-parent="#accordionExample"&gt;
        &lt;div class="card-body"&gt;
          Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird
          on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table,
          raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="card" id="contactCard"&gt;
      &lt;div class="card-header" id="headingThree"&gt;
        &lt;h5 class="mb-0"&gt;
          &lt;button class="btn btn-link collapsed" type="button" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree"&gt;
                                                  צור קשר
                                              &lt;/button&gt;
        &lt;/h5&gt;
      &lt;/div&gt;
      &lt;div id="collapseFive" class="collapse" aria-labelledby="headingThree" data-parent="#accordionExample"&gt;
        &lt;div class="card-body"&gt;
          Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird
          on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table,
          raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>can anyone take a look?</p>