</div>

        <div class="btn-group">

            <button class="btn btn-primary">按钮2</button>

        </div>

        <div class="btn-group">

            <button class="btn btn-primary">按钮3</button>

        </div>

    </div>

    <br><br>

    <div class="btn-group-vertical">

        <a href="#" class="btn btn-primary">按钮1</a>

        <a href="#" class="btn btn-primary">按钮2</a>

        <a href="#" class="btn btn-primary">按钮3</a>

    </div>

    <div class="btn-group-vertical btn-group-lg">

        <a href="#" class="btn btn-primary">按钮1</a>

        <a href="#" class="btn btn-primary">按钮2</a>

        <a href="#" class="btn btn-primary">按钮3</a>

    </div>

    <div class="btn-group-vertical btn-group-sm">

        <a href="#" class="btn btn-primary">按钮1</a>

        <a href="#" class="btn btn-primary">按钮2</a>

        <a href="#" class="btn btn-primary">按钮3</a>

    </div>

    <div class="btn-group-vertical btn-group-xs">

        <a href="#" class="btn btn-primary">按钮1</a>

        <a href="#" class="btn btn-primary">按钮2</a>

        <a href="#" class="btn btn-primary">按钮3</a>

    </div>

    <br><br>

    <a href="#" class="btn btn-primary">按钮 <span class="caret"></span></a>

    <button class="btn btn-primary">按钮 <span class="caret"></span></button>

    <input type="button" value="按钮" class="btn btn-primary"><span class="caret"></span>

    <div class="btn-group">

           <a href="#" class="btn btn-primary">按钮</a>

        <a href="#" class="btn btn-primary"><span class="caret"></span></a>

    </div>

    <div class="btn-group">

           <button class="btn btn-primary">按钮</button>

        <button class="btn btn-primary"><span class="caret"></span></button>

    </div>

    <div class="btn-group dropup">

           <button class="btn btn-primary">按钮</button>

        <button class="btn btn-primary"><span class="caret"></span></button>

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    <div class="github-style">

        <div class="btn-group btn-group-sm">

            <button class="btn btn-default active"><span class="glyphicon glyphicon-eye-open"></span> Watch <span class="caret"></span></button>

            <button class="btn btn-default">3,064</button>

        </div>

        <div class="btn-group btn-group-sm">

            <button class="btn btn-default active"><span class="glyphicon glyphicon-star"></span> Unstar</button>

            <button class="btn btn-default">36,296</button>

        </div>

        <div class="btn-group btn-group-sm">

            <button class="btn btn-default active"><span class="glyphicon icon-fork"></span> fork</button>

            <button class="btn btn-default">9,258</button>

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