CSS for long (scrolling) dropdown menu - html

Question

I'm trying to create a nested dropdown menu that may potentially be very long and overflow off the page.
What I'd like to do is, when the menu is too long it will display a scroll bar. I'm doing this with overflow: auto. However, when I do this, it traps any submenus within the same 'scroll space' as defined by the first scroll bar.
I've also tried various iterations of overflow: none with the :not(:hover) selector, but nothing I've tried seems to work.
What I'd like it to do is show the scrollbar on each level, only if necessary (i.e. that submenu would scroll off the page). Each submenu should 'pop' out of the previous scroll bar, if any, as if it was not there.
I'd like to do this in all CSS, but I'm open to a JS solution as well.
I have a code pen showing the issue here:
https://codepen.io/mcmurphy510/pen/ZyGLKd

Answer 1

I'm not sure if I'm understanding your question correctly, but try isolating your desired element by using ID or CLASS. See the third level menu.
#primary_nav_wrap {
margin-top: 15px
}
#primary_nav_wrap ul {
list-style: none;
position: relative;
float: left;
margin: 0;
padding: 0;
}
#primary_nav_wrap ul a {
display: block;
color: #333;
text-decoration: none;
font-weight: 700;
font-size: 12px;
line-height: 32px;
padding: 0 15px;
font-family: "HelveticaNeue", "Helvetica Neue", Helvetica, Arial, sans-serif
}
#primary_nav_wrap ul li {
position: relative;
float: left;
margin: 0;
padding: 0;
}
#primary_nav_wrap ul li.current-menu-item {
background: #ddd
}
#primary_nav_wrap ul li:hover {
background: #f6f6f6
}
#primary_nav_wrap ul ul {
display: none;
position: absolute;
top: 100%;
left: 0;
background: #fff;
padding: 0;
}
#primary_nav_wrap ul ul li {
float: none;
width: 200px
}
#primary_nav_wrap ul ul a {
line-height: 120%;
padding: 10px 15px
}
#primary_nav_wrap ul ul ul {
top: 0;
left: 100%
}
#primary_nav_wrap ul li:hover > ul {
display: block;
height: 200px;
}
#primary_nav_wrap ul li ul li:not(:hover) {
}
/* ul li ul li ul li {
overflow: auto;
} */
#subdeep {
overflow: auto;
height: 50px !important;
}
<h1>Simple Pure CSS Drop Down Menu</h1>
<nav id="primary_nav_wrap">
<ul>
<li>Menu 1
<ul>
<li>Sub Menu 1</li>
<li>Sub Menu 2</li>
<li>Sub Menu 3</li>
<li>Sub Menu 4
<ul>
<li>Deep Menu 1
<ul id="subdeep">
<li>Sub Deep 1</li>
<li>Sub Deep 2</li>
<li>Sub Deep 3</li>
<li>Sub Deep 4</li>
</ul>
</li>
<li>Deep Menu 2</li>
</ul>
</li>
<li>Sub Menu 5</li>
</ul>
</li>
</ul>
</nav>

Answer 2

Probably you could use the proposed solution as the elements are positioned relative to each other and therefore the menu can set up some branches, you would "just" require to ensure that the parent element(s) remain visible

Answer 3

Mouse over on item "Link 3" will shows its sub-menu on the right side of it and then mouse over on "Link 31" for further sub menu.
.menu {
position: relative;
}
ul {
width: 200px;
margin: 0;
color: black;
list-style:none;
padding:0;
max-height:100px;
overflow-x: hidden;
overflow-y: auto;
}
li {
padding:0.5em;
}
li:hover{
background-color:blue;
color:white;
}
li .menu {
position: absolute;
z-index: 10;
background-color:lightgrey;
opacity: 0;
transition: opacity 0.5s;
}
li:hover > .menu,
.menu:hover {
opacity: 1;
}
li.parent {
cursor: pointer;
}
.level2 {
top: 0px;
left: 200px;
}
<div class="menu">
<ul>
<li>Link1</li>
<li class="parent">Link3...
<div class="menu level2">
<ul>
<li class="parent">Link31...
<div class="menu level2">
<ul>
<li>Link 311</li>
<li>Link 312</li>
<li>Link 313</li>
<li>Link 314</li>
</ul>
</div>
</li>
<li>Link 32</li>
<li>Link 33</li>
<li>Link 34</li>
</ul>
</div>
</li>
<li>Link2</li>
<li>Link1</li>
<li>Link2</li>
</ul>
</div>