Changing others element's style with :target, html5 - html

Question

I'm using :target in html and I code something like that:
<div class="1">
<div>
<ul>
link to part 2
</ul>
</div>
<div class="ex">
<ul id="2">
<p>hi</p>
</ul>
</div>
and I've done this in css:
.ex ul {
display: none;
}
.ex ul:target {
display: block;
}
I need to make so that when you click on the link (in this case the words 'link to part 2') the #2 ul show, (alredy done this) and the ul whit the link disappears, how can I do?

Answer 1

One way this can be accomplished is with JavaScript. I added the id remove-on-click to your link which you want removed, and then created a JavaScript event listener to alter the style of this item when it is clicked. You can see the code working here.
<div class="1">
<ul>
link to part 2
</ul>
</div>
<div class="ex">
<ul id="2">
<p>hi</p>
</ul>
</div>
<script>
document.getElementById('remove-on-click').addEventListener('click',function(){
this.style.display = "none";
})
</script>
I did not edit any of your other code, but keep in mind that ul tag should be used with li descendants. If you do not have a li descendant, use another tag, such as a div. Also, you may want to become more familiar with proper naming of class and id attributes, especially in regards to not beginning them with a digit:
https://www.w3.org/TR/CSS2/syndata.html#characters
What are valid values for the id attribute in HTML?

Answer 2

The key consideration to note is that you must write the markup in reverse order.
This is because CSS selectors can only select:
an element itself (or a pseudo-element)
an element's descendant elements
an element's subsequent siblings
It cannot select an ancestor element or (in this scenario) a previous sibling.
Once you have written the markup in reverse order, you can achieve the effect you want using CSS.
Working Example:
#part2,
#part3 {
display: none;
}
#part2:target,
#part3:target {
display: block;
}
#part2:target ~ [id^="part"],
#part3:target ~ [id^="part"] {
display: none;
}
<div id="part3">
<p>This is Part 3.</p>
</div>
<div id="part2">
<p>This is Part 2.</p>
<ul>
<li>Link to Part 3</li>
</ul>
</div>
<div id="part1">
<p>This is Part 1.</p>
<ul>
<li>Link to Part 2</li>
</ul>
</div>