Answer as of 2020:
The best way (actually the only way*) to simulate an actual click event using only CSS (rather than just hovering on an element or making an element active, where you don't have mouseUp) is to use the checkbox hack. It works by attaching a label
to an <input type="checkbox">
element via the label's for=""
attribute.
This feature has broad browser support (the :checked
pseudo-class is IE9+).
Apply the same value to an <input>
's ID attribute and an accompanying <label>
's for=""
attribute, and you can tell the browser to re-style the label on click with the :checked
pseudo-class, thanks to the fact that clicking a label will check and uncheck the "associated" <input type="checkbox">
.
* You can simulate a "selected" event via the :active
or :focus
pseudo-class in IE7+ (e.g. for a button that's normally 50px
wide, you can change its width while active
: #btnControl:active { width: 75px; }
), but those are not true "click" events. They are "live" the entire time the element is selected (such as by Tabbing with your keyboard), which is a little different from a true click event, which fires an action on - typically - mouseUp
.
Basic demo of the checkbox hack (the basic code structure for what you're asking):
label {
display: block;
background: lightgrey;
width: 100px;
height: 100px;
}
#demo:checked + label {
background: blue;
color: white;
}
<input type="checkbox" id="demo"/>
<label for="demo">I'm a square. Click me.</label>
Here I've positioned the label right after the input in my markup. This is so that I can use the adjacent sibling selector (the + key) to select only the label that immediately follows my #demo
checkbox. Since the :checked
pseudo-class applies to the checkbox, #demo:checked + label
will only apply when the checkbox is checked.
Demo for re-sizing an image on click, which is what you're asking:
#btnControl {
display: none;
}
#btnControl:checked + label > img {
width: 70px;
height: 74px;
}
<input type="checkbox" id="btnControl"/>
<label class="btn" for="btnControl"><img src="https://placekitten.com/200/140" id="btnLeft" /></label>
With that being said, there is some bad news. Because a label can only be associated with one form control at a time, that means you can't just drop a button inside the <label></label>
tags and call it a day. However, we can use some CSS to make the label look and behave fairly close to how an HTML button looks and behaves.
Demo for imitating a button click effect, above and beyond what you're asking:
#btnControl {
display: none;
}
.btn {
width: 60px;
height: 20px;
background: silver;
border-radius: 5px;
padding: 1px 3px;
box-shadow: 1px 1px 1px #000;
display: block;
text-align: center;
background-image: linear-gradient(to bottom, #f4f5f5, #dfdddd);
font-family: arial;
font-size: 12px;
line-height:20px;
}
.btn:hover {
background-image: linear-gradient(to bottom, #c3e3fa, #a5defb);
}
.btn:active {
margin-left: 1px 1px 0;
box-shadow: -1px -1px 1px #000;
outline: 1px solid black;
-moz-outline-radius: 5px;
background-image: linear-gradient(to top, #f4f5f5, #dfdddd);
}
#btnControl:checked + label {
width: 70px;
height: 74px;
line-height: 74px;
}
<input type="checkbox" id="btnControl"/>
<label class="btn" for="btnControl">Click me!</label>
Most of the CSS in this demo is just for styling the label element. If you don't actually need a button, and any old element will suffice, then you can remove almost all of the styles in this demo, similar to my second demo above.
You'll also notice I have one prefixed property in there, -moz-outline-radius
. A while back, Mozilla added this awesome non-spec property to Firefox, but the folks at WebKit decided they aren't going to add it, unfortunately. So consider that line of CSS just a progressive enhancement for people who use Firefox.
:active
works while the mouse is down. Depending on what you're trying to do, you may be able to make it work using the CSS4 pseudo-class:target
. – bfavaretto:target
is not new to Selectors 4. It has been available since Selectors 3, which was already a recommendation for a year at the time of writing. – BoltClock♦