z-index and overflow doesn't work at all
<p>I was tried to set z-index, overflow, position absolute and rest css features but dropdown menu is still appearing in small square. thru console log, I figure out that some styles such as bootstrap-tabel.css and dropdown are conflicted between themselves and one style every time override other How could I fix it?</p>

<p><a href="https://plnkr.co/edit/libqkaSATjDVnJWj68Mq?p=preview" rel="nofollow">This my plunker</a></p>

<p>css</p>

<pre><code>.dropdown-menu&gt;li
{   position:relative;
    -webkit-user-select: none; /* Chrome/Safari */
    -moz-user-select: none; /* Firefox */
    -ms-user-select: none; /* IE10+ */
    /* Rules below not implemented in browsers yet */
    -o-user-select: none;
    user-select: none;
    cursor:pointer;
}
.dropdown-menu .sub-menu {
    left: 100%;
    position: absolute;
    top: 0;
    z-index: 999;
    overflow: visible;
    display:none;
    margin-top: -1px;
    border-top-left-radius:0;
    border-bottom-left-radius:0;
    border-left-color:#fff;
    box-shadow:none;

    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    -moz-overflow-scrolling: touch;
    -ms-overflow-scrolling: touch;
    -o-overflow-scrolling: touch;
    overflow-scrolling: touch;
    height: auto;
    max-height: 500px;
    border-left: none;
    border-right: none;
    -webkit-border-radius: 0 !important;
    -moz-border-radius: 0 !important;
    -ms-border-radius: 0 !important;
    -o-border-radius: 0 !important;
    border-radius: 0 !important;
    -webkit-box-shadow: none;
    -moz-box-shadow: none;
    -ms-box-shadow: none;
    -o-box-shadow: none;

}
.right-caret:after,.left-caret:after
{   content:"";
    border-bottom: 5px solid transparent;
    border-top: 5px solid transparent;
    display: inline-block;
    height: 0;
    vertical-align: middle;
    width: 0;
    margin-left:5px;
}
.right-caret:after
{   border-left: 5px solid #ffaf46;
}
.left-caret:after
{   border-right: 5px solid #ffaf46;
}
</code></pre>