-webkit-column-count: 3;
-webkit-column-gap: 10px;
-webkit-column-fill: auto;
-moz-column-count: 3;
-moz-column-gap: 10px;
-moz-column-fill: auto;
I am a beginner at CSS and when I was looking at some CSS code the other day, I found these lines. In the tutorials I used to learn CSS, I have never seen anything like these lines. Could someone please explain these lines to me or give me a source where I could learn to implement lines like these?
Answer
These are the vendor-prefixed properties offered by the relevant rendering engines (-webkit for Chrome, Safari; -moz for Firefox, -o for Opera, -ms for Internet Explorer). Typically they're used to implement new, or proprietary CSS features, prior to final clarification/definition by the W3.
This allows properties to be set specific to each individual browser/rendering engine in order for inconsistencies between implementations to be safely accounted for. The prefixes will, over time, be removed (at least in theory) as the unprefixed, the final version, of the property is implemented in that browser.
To that end it's usually considered good practice to specify the vendor-prefixed version first and then the non-prefixed version, in order that the non-prefixed property will override the vendor-prefixed property-settings once it's implemented; for example:
.elementClass {
-moz-border-radius: 2em;
-ms-border-radius: 2em;
-o-border-radius: 2em;
-webkit-border-radius: 2em;
border-radius: 2em;
}
Specifically, to address the CSS in your question, the lines you quote:
-webkit-column-count: 3;
-webkit-column-gap: 10px;
-webkit-column-fill: auto;
-moz-column-count: 3;
-moz-column-gap: 10px;
-moz-column-fill: auto;
Specify the column-count, column-gap and column-fill properties for Webkit browsers and Firefox.
References: