UPDATE January, 2017:

According to Can I use, the user-select + -webkit-user-select for Safari is enough to achieve desired behavior in all major browsers.

These are all of the available correct CSS variations:

.noselect {
  -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none; /* Safari */
     -khtml-user-select: none; /* Konqueror HTML */
       -moz-user-select: none; /* Old versions of Firefox */
        -ms-user-select: none; /* Internet Explorer/Edge */
            user-select: none; /* Non-prefixed version, currently
                                  supported by Chrome, Edge, Opera and Firefox */
}

<p>
  Selectable text.
</p>
<p class="noselect">
  Unselectable text.
</p>

Note that user-select is in standardization process (currently in a W3C working draft). It is not guaranteed to work everywhere and there might be differences in implementation among browsers. Also, browsers can drop support for it in the future.

More information can be found in Mozilla Developer Network documentation.

The values of this attribute are none, text, toggle, element, elements, all and inherit.

Until CSS 3's user-select property becomes available, Gecko-based browsers support the -moz-user-select property you already found. WebKit and Blink-based browsers support the -webkit-user-select property.

This of course is not supported in browsers that do not use the Gecko rendering engine.

There is no "standards" compliant quick-and-easy way to do it; using JavaScript is an option.

The real question is, why do you want users to not be able to highlight and presumably copy and paste certain elements? I have not come across a single time that I wanted to not let users highlight a certain portion of my website. Several of my friends, after spending many hours reading and writing code will use the highlight feature as a way to remember where on the page they were, or providing a marker so that their eyes know where to look next.

The only place I could see this being useful is if you have buttons for forms that should not be copy and pasted if a user copy and pasted the website.

You can do so in Firefox and Safari (Chrome also?)

::selection { background: transparent; }
::-moz-selection { background: transparent; }

With SASS (SCSS syntax)

You can do this with a mixin:

// Disable selection
@mixin disable-selection {
    -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none;   /* Safari */
    -khtml-user-select: none;    /* Konqueror HTML */
    -moz-user-select: none;      /* Firefox */
    -ms-user-select: none;       /* Internet Explorer/Edge */
    user-select: none;           /* Non-prefixed version, currently supported by Chrome and Opera */
}

// No selectable element
.no-selectable {
    @include disable-selection;
}

In an HTML tag:

<div class="no-selectable">TRY TO HIGHLIGHT. YOU CANNOT!</div>

Try it in this CodePen.

If you are using an autoprefixer you can remove other prefixes.

Browser compatibility here.

Aside from the Mozilla-only property, no, there is no way to disable text selection with just standard CSS (as of now).

If you notice, Stack Overflow doesn't disable text selection for their navigation buttons, and I would recommend against doing so in most cases, since it modifies normal selection behavior and makes it conflict with a user's expectations.

It is easily done with:

-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
-o-user-select: none;
user-select: none;

Alternatively:

Let's say you have a <h1 id="example">Hello, World!</h1>. You will have to remove the innerHTML of that h1, in this case Hello, World. Then you will have to go to CSS and do this:

#example::before // You can of course use **::after** as well.
{
    content: 'Hello, World!'; // Both single-quotes and double-quotes can be used here.

    display: block; // To make sure it works fine in every browser.
}

Now it simply thinks it is a block-element, and not text.

FIRST METHOD: ( TOTALLY NONSENSE ):

.no-select::selection, .no-select *::selection {
  background-color: Transparent;
}

.no-select { /* Sometimes I add this too. */
  cursor: default;
}

<span>RixTheTyrunt is da best!</span>
<br>
<span class="no-select">RixTheTyrunt is da best!</span>

Snippet:

.no-select::selection, .no-select *::selection {
  background-color: Transparent;
}

.no-select {
  /* Sometimes I add this too. */
  cursor: default;
}

<span>RixTheTyrunt is da best!</span>
<br>
<span class="no-select">RixTheTyrunt is da best!</span>

SECOND METHOD ( NO NONSENSE INCLUDED )

.no-select {
  user-select: none;
  -moz-user-select: none;
  -webkit-user-select: none;
}

Snippet:

.no-select {
  user-select: none;
  -moz-user-select: none;
  -webkit-user-select: none;
}

<span>RixTheTyrunt is da best!</span>
<br>
<span class="no-select">RixTheTyrunt is da best!</span>

First, solve the problem. Then, write the code.

John Johnson

If you want to disable selection and highlighting for the whole page with CSS, you can easily apply it to all elements:

* {
    -webkit-touch-callout: none; /* iOS Safari */
      -webkit-user-select: none; /* Safari */
       -khtml-user-select: none; /* Konqueror HTML */
         -moz-user-select: none; /* Firefox */
          -ms-user-select: none; /* Internet Explorer/Edge */
              user-select: none; /* Non-prefixed version, currently
                                    supported by Chrome and Opera */
}

Have you tried this?

.disableSelect{
    user-select: none;
    -webkit-user-select: none;
    -ms-user-select: none;
    -webkit-touch-callout: none;
    -o-user-select: none;
    -moz-user-select: none;

    pointer-events:none;
}

Add a class to your CSS that defines you cannot select or highlight an element. I have an example:

<style> 
    .no_highlighting{
        user-select: none;
    }

    .anchor_without_decoration:hover{
        text-decoration-style: none;
    }
</style>

<a href="#" class="anchor_without_decoration no_highlighting">Anchor text</a>

With CSS-

div {
  -moz-user-select: none;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
  -o-user-select: none;

  "unselectable='on' onselectstart="return false;"
  onmousedown="return false;
}

<div>
  Blabla
  <br/> More Blabla
  <br/> More Blabla...
</div>

I see many detailed answers but I believe that writing just this line of code should be enough for the required task:

*{
    -webkit-user-select: none;
 }

Even better, you can disable text selection.

If you like Sass (SCSS), and you don't want to use Compass you can do this:

styles.scss

@mixin user-select($select) {
    -webkit-touch-callout:#{$select};
    @each $pre in -webkit-, -moz-, -ms-, -o-, -khtml- {
        #{$pre + user-select}: #{$select};
    }
    #{user-select}: #{$select};
}

.no-select {
    @include user-select(none);
}

I combined the various browser CSS select attributes with the unselectable tag required for Internet Explorer < 9.

<style>
[unselectable="on"] {
    -webkit-user-select: none; /* Safari */
    -moz-user-select: none; /* Firefox */
    -ms-user-select: none; /* Internet Explorer 10+/Edge */
    user-select: none; /* Standard */
}
</style>
<div unselectable="on">Unselectable Text</div>

::selection {background: transparent; color: transparent;}

::-moz-selection {background: transparent; color: transparent;}

You may also want to prevent the context menu appearing when touching elements like buttons that have their selection prevented. To do that, add this code to the entire page, or just those button elements:

$("body").on("contextmenu",function(e){
    return false;
});

This may work

    ::selection {
        color: none;
        background: none;
    }
    /* For Mozilla Firefox */
    ::-moz-selection {
        color: none;
        background: none;
    }