biggatesとsteakpiに感謝します。Dreamonicの質問への回答として、すべてのヘッダーを(タイトル文字列とグループだけでなく)クリック可能にするように少し変更し、リンクから下線を外しました。アイコンを強制的に同じ行に表示するために、CSSの説明の最後にh4を追加しました。変更されたコードは次のとおりです。
<div class="panel-group" id="accordion">
<div class="panel panel-default">
<div class="panel-heading">
<a class="accordion-toggle collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseOne">
<h4 class="panel-title">Collapsible Group Item #1</h4>
</a>
</div>
<div id="collapseOne" class="panel-collapse collapse">
<div class="panel-body">
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.
</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<a class="accordion-toggle collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseTwo">
<h4 class="panel-title">Collapsible Group Item #2</h4>
</a>
</div>
<div id="collapseTwo" class="panel-collapse collapse">
<div class="panel-body">
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.
</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<a class="accordion-toggle collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseThree">
<h4 class="panel-title">Collapsible Group Item #3</h4>
</a>
</div>
<div id="collapseThree" class="panel-collapse collapse">
<div class="panel-body">
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.
</div>
</div>
</div>
</div>
そして変更されたCSS:
.panel-heading .accordion-toggle h4:after {
/* symbol for "opening" panels */
font-family: 'Glyphicons Halflings';
content: "\e114";
float: right;
color: grey;
overflow: no-display;
}
.panel-heading .accordion-toggle.collapsed h4:after {
/* symbol for "collapsed" panels */
content: "\e080";
}
a.accordion-toggle{
text-decoration: none;
}