How to strike through obliquely with css

There is a hacky way to do this, using the :before pseudo element. You give the :before a border, then rotate it with a CSS transform. Doing it this way adds no extra elements to the DOM, and adding/removing the strikethrough is a simple as adding/removing the class.

Here's a demo

Caveats

• This will only work down to IE8. IE7 does not support :before, however will degrade gracefully in browsers that do support :before but don't support CSS transforms.
• The angle of rotation is fixed. If the text is longer, the line will not touch the corners of the text. Be mindful of this.

CSS

.strikethrough {
  position: relative;
}
.strikethrough:before {
  position: absolute;
  content: "";
  left: 0;
  top: 50%;
  right: 0;
  border-top: 1px solid;
  border-color: inherit;
  
  -webkit-transform:rotate(-5deg);
  -moz-transform:rotate(-5deg);
  -ms-transform:rotate(-5deg);
  -o-transform:rotate(-5deg);
  transform:rotate(-5deg);
}

HTML

<span class="strikethrough">Deleted text</span>

You can use background linear-gradient with currentColor to avoid hardcoding font color:

.strikediag {
  background: linear-gradient(to left top, transparent 47.75%, currentColor 49.5%, currentColor 50.5%, transparent 52.25%);
}
.withpadding {
  padding: 0 0.15em;
}

The value is <span class="strikediag">2x</span> 3x<br>
The number is <span class="strikediag">1234567890</span>.
<p>
The value is <span class="strikediag withpadding">2x</span>3x<br>
The number is <span class="strikediag withpadding">1234567890</span>.

If you don't need the element to be fully inline, you can use a pseudo element to place the line on top of the element. This way the angle can be adjusted by changing the pseudo element's size:

.strikediag {
  display: inline-block;
  position: relative;
}
.strikediag::before {
  content: '';
  position: absolute;
  left: -0.1em;
  right: -0.1em;
  top: 0.38em;
  bottom: 0.38em;
  background: linear-gradient(to left top, transparent 45.5%, currentColor 47.5%, currentColor 52.5%, transparent 54.5%);
  pointer-events: none;
}

The value is <span class="strikediag">2x</span> 3x<br>
The number is <span class="strikediag">1234567890</span>.