问jquery ui选项卡不显示除第一个选项卡之外的任何内容

EN

<div id="tabset">
    <ul> 
        <li><a href="#policytab">Policy</a></li>
        <li><a href="#backgroundtab">Background</a></li>
    </ul>
<div id="policytab">
    <div class="panel cflex">
        <div class="textdiv" contenteditable="true">xx</div>
        <div>
            <div class="lrflex">
            <div>L1</div>
            <div class="rflex">
                <div>R1</div>
                <div>R2</div>
            </div>
        </div>
    </div>
</div>
<div id="backgroundtab">
    <div class="panel cflex">
        <div class="textdiv" contenteditable="true">xx</div>
        <div>
            <div class="lrflex">
            <div>L1</div>
            <div class="rflex">
                <div>R1</div>
                <div>R2</div>
            </div>
        </div>
    </div>
</div>
</div>

.panel {
    height: 200px;
    border: 1px solid red;
    resize: both;
    overflow: auto;
}
.textdiv {
    border: 1px solid red;
    height: 1500px;
    overflow: auto;
}
.cflex {
    display: flex;
    flex-direction: column;
}
.rflex {
    display: flex;
    flex-direction: row;
    align-items: flex-end;
    border: 1px solid purple;
}
.lrflex {
    display: flex;
    flex-direction: row;
    align-items: flex-end;
    justify-content: space-between;
    border: 1px solid green;
}

$("#tabset").tabs();