Responsive Separator for Horizontal List

Question

This question expands upon 'Separators For Navigation' by asking, how it is possible to remove the separators at the line breaks cause by viewport size.

Wide Viewport

->       Item 1 | Item 2 | Item 3 | Item 4 | Item 5       <-

Small Viewport

->  Item 1 | Item 2 | Item 3  <-
->      Item 4 | Item 5       <-

Here is a fiddle that shows how a pipe remains at the line break:

Fiddle.

I'm interested in a css-only solution, but javascript is acceptable if it provides the only possible solution.

Answer 1

Explanation

You can exploit fact that trailing and line trailing white space automatically collapses:

document.write(`<div>`
+ `word<b> </b>`.repeat(42)
+ `</div>`);

b {
    background: red;
    outline: 1px solid blue;
}
div {
    resize: both;
    overflow: hidden;
}

As you can see, there are red spaces with blue outlines between words, but the very last and and those at line ends lack the red area, because its width collapsed to zero: that is the white-space collapsing in effect.

It is possible to adjust width with word-spacing and use pseudo element instead, so setting ::after { content: ' '; word-spacing: 2em; } gives you wide inline rectangle that can display decorated backgrounds but disappears when not between two words on same line.

Simplified example

Simplified use case (from https://codepen.io/myf/pen/dyOzpZM, tested just in 2021-02 evergreen Firefox and Chromium, will not work in pre-Chromium Edge; for more robust example see the second snippet below):

ul {
  text-align: center;
  padding: 0;
}
li {
  display: inline;
}
li::after {
  /*
   This has to be space, tab or other
   breakable white-space character:
  */
  content: " ";
  word-spacing: 1em;
  background-image: linear-gradient(
    -0.2turn,
    transparent 0 calc(50% - 0.03em),
    currentcolor 0 calc(50% + 0.03em),
    transparent 0
  );
}
/*
 That's it: just inline text
 with styled ::after spaces
 that collapse at line breaks
 and at the end of the element.
 
 That's basically how spaces work in text.
*/

/*
 Unrelated whimsical effects:
*/
body { background: #456; color: #fed; min-height: 100vh; margin: 0; display: flex; align-items: center; }
ul { --dur: 3s; font-family: Georgia, serif; font-size: min(7vw, calc(100vh / 7)); margin: 0 auto; position: relative; padding: 0 1em; -webkit-text-fill-color: #999; text-transform: capitalize; animation: poing var(--dur) infinite alternate ease-in-out; }
@keyframes poing { from { max-width: 3.4em; } to { max-width: min(19em, calc(100vw - 2em)); color: lime; } }
ul::before, ul::after { -webkit-text-fill-color: currentcolor; position: absolute; top: 50%; transform: translatey(-50%); animation: calc(var(--dur) * 2) calc(var(--dur) * -1.5) infinite forwards linear; }
ul::before { content: "☜"; left: 0; animation-name: a !important; }
ul::after { content: "☞"; right: 0; animation-name: b !important; }
@keyframes a { 50% { content: "☛"; } }
@keyframes b { 50% { content: "☚"; } }
ul:hover, ul:hover::before, ul:hover::after { animation-play-state: paused; }

<ul>
 <li>foo</li>
 <li>bar</li>
 <li>baz</li>
 <li>gazonk</li>
 <li>qux</li>
 <li>quux</li>
</ul>

It uses flat list with single-word items.

More complex example with elements highlights

nav {
  text-align: center;
  padding-right: 1em; /* = li::after@word-spacing */
}
ul {
  display: inline;
  margin: 0;
  padding: 0;
}
li {
  display: inline;
  /*
   white-space: nowrap should be moved to child A
   because IE fails to wrap resulting list completely
  */
}
li::before {
  content: ' ';
  /*
   this content is important only for Chrome in case
   the HTML will be minified with *no whitespaces* between </li><li>
  */
}
li::after {
  content: ' ';
  /*
   this is actual placeholder for background-image
   and it really must be space (or tab)
  */
  white-space: normal;
  word-spacing: 1em;
  /*
   = nav@padding-right - this actually makes width
  */
  background-image: radial-gradient(circle, black, black 7%, transparent 15%, transparent 35%, black 45%, black 48%, transparent 55%);
  background-size: 1em 1em;
  background-repeat: no-repeat;
  background-position: center center;
  opacity: 0.5;
}
/*
 no need to unset content of li:last-child::after
 because last (trailing) space collapses anyway
*/
a {
  white-space: nowrap;
  display: inline-block; /* for padding */
  padding: 1em;
  text-decoration: none;
  color: black;
  transition-property: background-color;
  transition-duration: 500ms;
}
a:hover {
  background-color: #ccc;
}
/*
 For demonstrative purposes only
 Give items some content and uneven width
*/
nav:hover > ul > li {
  outline: 3px dotted rgba(0,0,255,.5);
  outline-offset: -3px;
}
nav:hover > ul > li::after {
  opacity: 1;
  background-color: rgba(255, 0, 0, .5);
}
nav:hover > ul > li:hover {
  outline-style: solid;
}
nav:hover > ul > li:hover::after  {
  background-color: cyan;
}

nav:hover > ul > li > a {
  outline: 3px solid rgba(0,255,0,.5);
  outline-offset: -3px;
}

nav > ul {
  counter-reset: c;
}
nav > ul > li {
  counter-increment: c;
}
nav > ul > li > a::before {
  content: counter(c, upper-roman) '. ';
  letter-spacing: .3em;
}
nav > ul > li > a::after {
  content: ' item ' counter(c, lower-roman);
  word-spacing: .3em;
  letter-spacing: .1em;
  transform: translatex(.1em);
  display: inline-block;
}

<nav>
  <ul><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></li>
  </ul>
</nav>
<!--  For demonstrative purposes is content of links made by CSS
-->

(Originally from https://jsfiddle.net/vnudrsh6/7/) This proof-of-concept uses background-image of "eventually collapsing" CSS generated content space after each <li>. Tested in 2016 in Firefox, Chrome and IE11.

---

You might need to use some character or more complex shape as divider (separator). Naturally you can use (vector) background-image, and you can even use text in SVG, although making it aligned to surrounding ("real") text might be challenging.

Bare-bones with SVG

Minimal working example without any "list" element, with textual ❦ fleuron:

body {
  text-align: center;
}
b::after {
  content: " ";
  word-spacing: 16px;
  background: url("data:image/svg+xml;charset=utf-8,\
  <svg xmlns='http://www.w3.org/2000/svg' \
    viewBox='-3,-15,16,16'>\
      <text>❦</text>\
  </svg>");
}
div {
    resize: both;
    overflow: hidden;
}

<div>
<b>foo</b> <b>bar</b> <b>baz</b> <b>gazonk</b> <b>qux</b> <b>quux</b> 
<b>foo</b> <b>bar</b> <b>baz</b> <b>gazonk</b> <b>qux</b> <b>quux</b> 
<b>foo</b> <b>bar</b> <b>baz</b> <b>gazonk</b> <b>qux</b> <b>quux</b>
</div>

Justified block

If you need to have spaced items making straight side lines producing justified text block, text-align-last in addition to text-align: justify may come in handy. Conveniently, it's the white space "character" yet again what makes the "stretching" adjustments here:

ul {
  text-align: center;
  padding: 0;
  font-size: 30px;
  text-align: justify;
  text-align-last: justify;
  overflow: hidden;
  resize: both
}

li {
  display: inline;
}

li::after {
  content: " ";
  background-color: highlight;
  word-spacing: 3em;
  background-image: linear-gradient(
    0.25turn,
    transparent 0 calc(50% - 0.03em),
    mark 0 calc(50% + 0.03em), transparent 0
  );
}

html {
  color-scheme: light dark;
}

<ul>
  <li>foo</li>
  <li>bar</li>
  <li>baz</li>
  <li>gazonk</li>
  <li>qux</li>
  <li>quux</li>
</ul>

---

Other notable answers:

• Same technique used in overlooked Liphtier's answer from 2014. (I've found that one long after posting this answer, so to my disappointment I cannot claim my answer published it first.)
• Same technique used few months later in Tom Robinson's answer.
• Impressive flex-box-based solution with plain over-extending borders and different spacing in gfullam's answer.
• For left-aligned list you can set overflow hidden and cut overlapping real character in pseudo element: Oriol's answer and Nathan Arthur's. .

Answer 2

My implementation with JavaScript: https://jsfiddle.net/u2zyt3vw/5/

Hit "Run" again after you've resized the window.

You can also add event listeners such as onresize. Here's the JS:

var listItems = document.getElementsByTagName("li");
var listItemsWidth = [];
var listItemsDistance = [];

for (let i = 0; i < listItems.length; i++) {
  listItemsWidth[i] = listItems[i].offsetWidth;
  listItemsDistance[i] = listItems[i].getBoundingClientRect().right;
}

for (let i = 0; i < listItems.length; i++) {
  if (listItemsDistance[i] == Math.max.apply(null, listItemsDistance)) {
    listItems[i].classList -= "notLast";
  } else {
    listItems[i].classList = "notLast";
  }
}

I added the notLast class to all of your elements, and that's what contains the :after pseudo-element with the pipe. This script removes this class from the ones that are closer to the right edge of the container.

I also messed around with the :after pseudo-element and made it position:absolute; for dark reasons.

Answer 3

Nice question. For the life of me, I can't think of a water-tight CSS-only solution I'm afraid...

I've modified an old solution to a similar question posted a while back: CSS: Last element on line. Funnily enough I was looking for a solution to another problem I had a while back and stumbled across this - been bookmarked since!

Here's a fiddle with my updates: https://jsfiddle.net/u2zyt3vw/1/

HTML:

<ul>
  <li>Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>
  <li>Item 4</li>
  <li>Item 5</li>
</ul>

CSS:

body {
  text-align: center;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

li {
  display: inline-block;

  &:not(:last-child):after {
    content: ' |'

  }

}
li.remove:after {
  content: none;
}

jQuery:

$(window).on("resize", function () {
    var lastElement = false;
    $("ul > li").each(function() {
        if (lastElement && lastElement.offset().top != $(this).offset().top) {
            lastElement.addClass("remove");
        }
        lastElement = $(this);
    }).last().addClass("remove");
}).resize();

NOTE - it works best onload at the moment, resizing causes a few issue even if I use toggleClass(). So keep pressing "Run" every time you resize the view. I'll work on it and get back to you..

Answer 4

A different solution from that same CSS: Last element on line seems like it would work here.

HTML:

<div>
<ul>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
</ul>
</div>

CSS:

div {overflow: hidden; margin: 1em; }
div ul { list-style: none; padding: 0; margin-left: -4px; }
div ul li { display: inline; white-space: nowrap; }
div ul li:before { content: " | "; }

(Fiddle)

Answer 5

If you have static width of your element you can calculate by the media-screen. If not use script

body {
  text-align: center;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

li {
  display: inline-block;

  &:not(:last-child):after {
  content: ' |';  
  }
}
@media screen and (max-width: 265px) {
  li {
  display: inline-block;

  &:not(:last-child):after {
  content: '';  
  }
}

}