I'm trying to find a way to create a custom highlight in CSS that takes up ~50% of the text height, centered vertically, that also works over multiple lines. I can do it a few ways that work on a single line, but all fall over when applied to multi line text, or aren't able to vertically center.

```css
hr {
  margin: 15px 0;
}

.title-psuedo .background {
  position: relative;
  padding-left: 40px;
  padding-right: 40px;  
}

.title-psuedo .background:after {
  content: "";
  position: absolute;
  width: 100%;
  background: yellow;
  left: 0;
  bottom: 0.3em;
  height: 0.4em;
  z-index: -1;
}

.title-mark mark {
  display: inline-block;
  line-height: 0em;
  padding-bottom: 0.5em;
  padding-left: 40px;
  padding-right: 40px;  
}

.title-shadow .background {
  box-shadow: inset 0 -0.5em 0 yellow;
  padding-left: 40px;
  padding-right: 40px;  
}

.title-background .background {
  padding: 0 40px;
  line-height: 0.5em;
  margin: 0.25em 0;
  background-color: yellow;
  display: inline-block;
}
```

```html
<div class="title title-psuedo">
  <span class="background">This is the desired effect.</span>
</div>

<hr>

<div class="title title-psuedo">
  <span class="background">This works on one line, but not when the text spans onto 2 separate lines, as the background messes up and only appears on the last line of the content.</span>
</div>

<hr>

<div class="title title-mark">
  <mark>This works on one line, but not when the text spans onto 2 separate lines, as the lines merge into one single line which isn't legible. Also, I'm not sure the highlight can be centered vertically.</mark>
</div>

<hr>

<div class="title title-shadow">
  <span class="background">This works on multiple lines, but I'm not sure the highlight can be centered vertically. Additionally, the second line does not have the same padding as the first.</span>
</div>

<hr>

<div class="title title-background">
  <span class="background">This works on one line, but not when the text spans onto 2 separate lines as the line height collapses the text together and the highlight covers both lines without a gap. The second line does have the initial padding however.</span>
</div>
```