Let's finally take a look at the source of the problem
The checkboxes are rendered using images (one may set custom ones via CSS). Here is an (unchecked) checkbox in FireFox, highlighted with DOM inspector:
And here's the same unstyled checkbox in Chrome:
You can see the margin (orange); padding is not present (would be shown green). So what's this pseudo-margin on the right and on the bottom of the checkbox? These are parts of the image used for the checkbox. That's why using just vertical-align: middle
doesn't really suffice and that's the source of the cross-browser problems.
So what can we do about this?
One obvious option is – replace the images! Fortunately, one can do this via CSS and replace those with external images, base64 (in-CSS) images, in-CSS svg or just pseudo-elements. It's a robust (cross-browser!) approach, and here's an example of such adjustment stolen from this question:
.checkbox-custom {
opacity: 0;
position: absolute;
}
.checkbox-custom,
.checkbox-custom-label {
display: inline-block;
vertical-align: middle;
margin: 5px;
cursor: pointer;
}
.checkbox-custom + .checkbox-custom-label:before {
content: '';
display: inline-block;
background: #fff;
border-radius: 5px;
border: 2px solid #ddd;
vertical-align: middle;
width: 10px;
height: 10px;
padding: 2px;
margin-right: 10px;
text-align: center;
}
.checkbox-custom:checked + .checkbox-custom-label:before {
width: 1px;
height: 5px;
border: solid blue;
border-width: 0 3px 3px 0;
transform: rotate(45deg);
-webkit-transform: rotate(45deg);
-ms-transform: rotate(45deg);
border-radius: 0px;
margin: 0px 15px 5px 5px;
}
<div>
<input id="checkbox-1" class="checkbox-custom" name="checkbox-1" type="checkbox">
<label for="checkbox-1" class="checkbox-custom-label">First Choice</label>
</div>
<div>
<input id="checkbox-2" class="checkbox-custom" name="checkbox-2" type="checkbox">
<label for="checkbox-2" class="checkbox-custom-label">Second Choice</label>
</div>
You may want to read some more in-depth articles about such styling like some listed here; it's out of scope of this answer.
Ok, still what about no-custom-images-or-pseudo-elements solution?
TL;DR: looks like this won't work, use custom checkbox instead
First, let's notice that if in other browsers those pseudo-margins inside checkbox icon were arbitrary, there were no consistent solution. To build one, we have to explore the anatomy of such images in existing browsers.
So what browsers do have the pseudo-margins in checkboxes? I've checked out Chrome 75, Vivaldi 2.5 (Chromium-based), FireFox 54 (don't ask why such outdated), IE 11, Edge 42, Safari ?? (borrowed one for a minute, forgot to check out the version). Only Chrome and Vivaldi has such pseudo-margins (I suspect all Chromium-based browsers as well, like Opera).
What's the size of those pseudo-margins? To figure this out one can use a zoomed checkbox:
input {
zoom: 10;
box-shadow: 0 0 1px inset #999;
}
<input type=checkbox>
my result is ~7% of width/height and hence 0.9-1.0px in absolute units. The accuracy may be questioned, though: try different values of zoom
for the checkbox. In my tests in both Chrome and Vivaldi the relative size of the pseudo-margin is very different at zoom
values 10, 20 and at values 11-19 (??):
scale
seems to be more consistent:
input {
transform: scale(10) translate(50%, 50%);
box-shadow: 0 0 1px inset #999;
}
<input type=checkbox>
so probably ~14% and 2px are the correct values.
Now that we know (?) the size of the pseudo-margin, let's note this is not enough. Are the sizes of the checkbox icons the same for all browsers? Alas! Here's what DOM inspector shows for unstyled checkboxes:
- FireFox: 13.3px
- Chromium-based: 12.8px for the whole thing, hence 12.8 (100% - 14%) = 11px for what is visually perceived as checkbox
- IE 11, Edge: 13px
- Safari: n/a (these should be compared on the same screen, I believe)
Now before we discuss any solutions or tricks, let's ask: what is a correct alignment? What are we trying to achieve? To certain point it's a matter of taste, but basically I can think of the following "nice" alignments' aspects:
text and checkbox on the same baseline (I deliberately don't adjust checkbox size here):
or have same middle line in terms of lowercase letters:
or same middle line in terms of capital letters (it's easier to see the difference for different font size):
and also we have to decide whether the size of the checkbox should be equal to the height of a lowercase letter, a capital letter or something else (bigger, smaller or between lowercase and capital).
For this discussion let's call an alignment nice if the checkbox is on the same baseline as the text and has the size of a capital letter (a highly arguable choice):
Now what tools do we have to:
- adjust checkbox size
- recognize Chromium with its pseudo-margined checkbox and set specific styles
- adjust checkbox/label vertical alignment
?
Regarding the checkbox size adjustment: there are width
, height
, size
, zoom
, scale
(have I missed something?). zoom
and scale
don't allow to set absolute size, so they may help only with adjusting to text size, not set cross-browser size (unless we can write browser-specific rules). size
doesn't work with Chrome (did it work with old IE? anyway, it's not that interesting). width
and height
work in Chrome and other browsers, so we can set a common size, but again, in Chrome it sets the size of the whole image, not the checkbox itself. Note: it is minimum(width, height) which defines a checkbox's size (if width ≠ height, the area outside checkbox square is added to "pseudo-margin").
An unfortunate thing is, the pseudo-margins in Chrome checkbox are not set to zero for any width and heights, as far as I can see.
I'm afraid there's no reliable CSS-only method these days.
Let's consider vertical alignment. vertical-align
can't give consistent results when set to middle
or baseline
because of the Chrome's pseudo-margin, the only real option to get the same "coordinate system" for all the browsers is to align label and input to the top
:
(on the picture: vertical-align: top, bottom and bottom without box-shadow)
So what result do we get from this?
input[type="checkbox"] {
height: 0.95em;
width: 0.95em;
}
label, input {
vertical-align: top;
}
<label><input type="checkbox">label</label>
The snippet above works with Chrome (Chromium-based browsers), but other browsers require a smaller size of the checkbox. It seems to be impossible to adjust both the size and vertical alignment in a way that works around Chromium's checkbox image quirk. My final suggestion is: use custom checkboxes instead – and you'll avoid frustration :)
height
andline-height
attributes, give a look to jsfiddle.net/wepw5o57/3 – TheGr8_Nikposition
andtop
will solve this problem Example: jsfiddle.net/ynkjc22s – Profesor08