我尝试为具有固定位置的左侧边栏实现自定义滚动条，但滚动条不起作用。谁能向我解释为什么不起作用？我试图“强制”内部位置，但没有出现任何内容。
看看jsfiddle：
https://jsfiddle.net/1tpaeb4b/3/
(function($){
$(window).load(function(){
$(".content").mCustomScrollbar(
{
alwaysShowScrollbar: 2,
axis: "y",
scrollbarPosition: "inside"
});
});
})(jQuery);#sidebar-left-container{
position: fixed;
height: auto;
width: 25%;
min-width:250px;
bottom: 0;
top:0;
left: 0;
background-color: #fff;
color: #808080;
padding: 15px;
}
#sidebar-left-container h2{
margin-top: 0;
font-size: 1.4em;
}
.truncate{
width: 100%;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
}
body{
background-color: #f1f1f1;
} <div id="sidebar-left-container">
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<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
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<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
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<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
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<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
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<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
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</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
<div class="media messages">
<div class="media-left">
<a href=""><img src="/img/avatar-small.png" alt="avatar" class="img-circle pull-left message-img margin-right-15px" /></a>
</div>
<div class="media-body position-relative">
<a href=""><h4 class="media-heading"><strong>Alessandro Corradini</strong></h4></a>
<p class="message-text truncate">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed est elit, vulputate vitae dignissim non, varius vitae purus. Praesent quis augue malesuada, malesuada est eu, cursus metus.</p>
</div>
</div>
</div>
</div>