html – Bootstrap Accordion – 开始全部关闭

所以我的页面上有一个bootstrap风格的手风琴 – 但是一开始,第一个面板是打开的.
如何才能使它在加载页面时全部关闭？

任何帮助将非常感激！非常感谢！

<div class="panel-group" id="accordion">
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel1"><i class="fa fa-minus text-priMary"></i> Overview</a>
            </h4>
        </div>
        <div id="panel1" class="panel-collapse collapse in">
            <div class="panel-body">Contents panel 1</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel2"><i class="fa fa-plus text-priMary"></i> Utilities</a>
            </h4>
        </div>
        <div id="panel2" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 2</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel3"><i class="fa fa-plus text-priMary"></i> Organization</a>
            </h4>
        </div>
        <div id="panel3" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 3</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel4"><i class="fa fa-plus text-priMary"></i> Integrations</a>
            </h4>
        </div>
        <div id="panel4" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 3</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel5"><i class="fa fa-plus text-priMary"></i> Essentials</a>
            </h4>
        </div>
        <div id="panel5" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 3</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel6"><i class="fa fa-plus text-priMary"></i> SALEs</a>
            </h4>
        </div>
        <div id="panel6" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 3</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel7"><i class="fa fa-plus text-priMary"></i> Support</a>
            </h4>
        </div>
        <div id="panel7" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 3</div>
        </div>
    </div>
    <div class="panel panel-default">
        <div class="panel-heading">
            <h4 class="panel-title">
                <a class="accordion-toggle text-normalize" data-toggle="collapse" data-parent="#accordion" href="#panel8"><i class="fa fa-plus text-priMary"></i> Projects</a>
            </h4>
        </div>
        <div id="panel8" class="panel-collapse collapse">
            <div class="panel-body">Contents panel 3</div>
        </div>
    </div>
</div>

<div id="panel1" class="panel-collapse collapse">
   <div class="panel-body">Contents panel 1</div>
</div>