.wrapper
 %ul.items
  - (1...5).each do
   %li
    %a{:href => "#"} Lorem ipsum
    %ul.sub-items
     - (1...3).each do
      %li
       %a{:href => "#"} Lorem ipsum dolor sit amet.
View Compiled
/*
 * Developer: Alireza Eskandarpour Shoferi
 * Designer: Nevide (codecanyon.net/user/Nevide)
 *
 * Distributed under the terms of the MIT license
 * https://opensource.org/licenses/MIT
 */

@blueColor: #64D7E2;
@hover: #8EE8F1;
ul {
    margin: 0;
    padding: 0;
    list-style-type: none;
}
a {
    color: #646464;
    text-decoration: none;
}
body {
    background-color: @blueColor;
    font-family: "Source Sans Pro", sans-serif;
}
.wrapper {
    position: absolute;
    top: 50%;
    left: 50%;
    margin-top: -140px;
    margin-left: -140px;
    width: 280px;
    background-color: #fff;
    box-shadow: 0 4px 10px #7A9BAC;
    font-size: 0.875em;
}
.items {
    padding: 18px 0;
}
.items > li > a {
    display: block;
    margin: 0 auto;
    width: 90%;
    text-indent: 18px;
    line-height: 39px;
}
.items > li > a::after {
    position: absolute;
    right: 30px;
    margin-top: 2px;
    font-family: "FontAwesome"
}
.items > li > a::after {
    right: 30px;
    content: "\f061";
}
.itemHover {
    color: #fff;
    font-weight: 600;
    transition: background-color .4s ease-in-out;
}
.items > li > a:hover {
    background-color: @hover;
    .itemHover
}
.items > li > a.expanded {
    background-color: @blueColor;
    .itemHover
}
.items > li > a.expanded::after {
    content: "\f063";
}
.sub-items > li:first-child > a {
    margin-top: 17px;
    height: 34px;
}
.sub-items > li:last-child > a {
    margin-bottom: 17px;
    height: 34px;
}
.sub-items a {
    position: relative;
    display: block;
    margin: 0 auto;
    width: 212px;
    text-indent: 24px;
    line-height: 39px;
}
.sub-items a {
    border-left: 2px solid @blueColor;
}
.sub-items .current {
    position: relative;
    color: @blueColor;
    border-color: white;
}
.sub-items > li:hover > a {
    color: @blueColor;
    transition: color 0.4s ease-in-out;
}
.sub-items {
    display: none;
}
View Compiled
$(".items > li > a").click(function(e) {
    e.preventDefault();
    var $this = $(this);
    if ($this.hasClass("expanded")) {
        $this.removeClass("expanded");
    } else {
        $(".items a.expanded").removeClass("expanded");
        $this.addClass("expanded");
        $(".sub-items").filter(":visible").slideUp("normal");
    }
    $this.parent().children("ul").stop(true, true).slideToggle("normal");
});

$(".sub-items a").click(function() {
    $(".sub-items a").removeClass("current");
    $(this).addClass("current");
});

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js