Why line-height in Firefox and Chrome is different? - html

Question

I created multi-line-padded text based on Matthew Pennell's solution (codepen by CSS Tricks). In Chrome all looks fine, but in Firefox height of span elements bigger than height of their ancestor. If I adjust vertical padding for Firefox, in Chrome will be same problem, and vice versa.
Why it happens? What the real technical reasons of this problem?
HTML Code:
<div class="padded-multiline">
<h1>
<strong>How do I add padding to subsequent lines of an inline text element?</strong>
</h1>
</div>
CSS Code:
:root {
font-family: Arial, sans-serif;
font-size: 20px;
}
.padded-multiline {
line-height: 1.3;
padding: 2px 0;
border-left: 20px solid #c0c;
width: 400px;
margin: 20px auto;
}
.padded-multiline h1 {
background-color: #c0c;
padding: 4px 0;
color: #fff;
display: inline;
margin: 0;
}
.padded-multiline h1 strong {
position: relative;
left: -10px;
}

Answer 1

Setting a line-height: 1; on strong will fix the problem also read my comment.

Answer 2

Chrome and Firefox seems to use different text layout system.
In Chrome it will floor the line-height attribute and Firefox seems to use the correct one.

Answer 3

To achieve the same effect for title, just use only the outline.
H1 does not need strong.
.padded-multiline {
line-height: 1.3;
padding: 2px 0;
width: 400px;
margin: 20px auto;
}
.padded-multiline h1 {
background-color: #c0c;
padding:1px;
color: #fff;
display: inline;
outline: 10px solid #c0c;
margin: 0;
font-size:16px;
}
<div class="padded-multiline">
<h1>How do I add padding to subsequent lines of an inline text element?</h1>
</div>
Here is codepen: http://codepen.io/anon/pen/vgRvjM
If you need exactly visual (that means less purple space from top and bottom, you can use for example border from after and before):
.padded-multiline:before{
content:'';
display:block;
border:5px solid #fff;
position:relative;
left:-10px;
top:-3px;
}
.padded-multiline:after{
content:'';
display:block;
border:5px solid #fff;
position:relative;
left:-10px;
bottom:-3px;
}
Codepen for this solution: http://codepen.io/anon/pen/QdmzxK

Answer 4

Unfortunately, there isn't a full and clean crossbrowser workaround. Because different UAs render text different, height of each textline may be taller a bit (or vice verca). So, I create a solution based on SCSS calculations of required box' sizes, and hide artefacts via overflow property.
Here is my solution, if you meet the same problem: http://codepen.io/ifiri/pen/ygEeeL
HTML:
<p class="multiline-text">
<span class="multiline-text__wrapper multiline-text__wrapper--outer">
<span class="multiline-text__wrapper multiline-text__wrapper--left">
<span class="multiline-text__wrapper multiline-text__wrapper--right">Multiline Padded text, which looks great on all browsers. No artefacts, no hacks, all clear and flexy, all alignment support. Change SCSS variables for see how it works.</span>
</span>
</span>
</p>
SCSS:
/*
Variables
*/
$base-line-height: 1.75;
$base-font-size: 1.25em;
$multiline-padding-base: ($base-line-height / 2) * 1em;
$multiline-padding-horizontal: $multiline-padding-base;
$multiline-padding-vertical: $multiline-padding-base - (1em / 2);
$multiline-bg-color: #a5555a;
$multiline-font-color: #fff;
/*
= Snippet Styles
This code is required
*/
.multiline-text {
color: $multiline-font-color;
padding: 0px $multiline-padding-horizontal;
// hide line-height artefacts
overflow: hidden;
position: relative;
}
.multiline-text__wrapper {
background-color: $multiline-bg-color;
padding: $multiline-padding-vertical 0px;
}
.multiline-text__wrapper--outer {
// Inner padding between text lines
line-height: $base-line-height;
}
.multiline-text__wrapper--left {
position: relative;
left: -($multiline-padding-horizontal);
}
.multiline-text__wrapper--right {
position: relative;
right: -($multiline-padding-horizontal / 2);
}