Add strikethrough to checked checkbox

The :checked CSS pseudo-class selector represents any radio (<input type="radio">), checkbox (<input type="checkbox">) or option (<option> in a <select>) element that is checked or toggled to an on state. The user can change this state by clicking on the element, or selecting a different value, in which case the :checked pseudo-class no longer applies to this element, but will to the relevant one.

Source: https://developer.mozilla.org/en-US/docs/Web/CSS/%3Achecked

In order to make it work, rearrange your HTML to:

<div class="form-group ">
    <label for="inputName" class="col-md-1 control-label">select</label>  
    <div class="col-md-5">
        <div class="checkbox">
          <input name="packersOff" class="strikethrough" value="1" type="checkbox">
          <label for="packersOff">sssssssss</label>
        </div>
     </div>
</div>

And your CSS to:

.strikethrough:checked + label {
  text-decoration:line-through
}

DEMO.

Problem is that you are trying to apply line-through on checkbox where as the text is inside the label. You can wrap the text inside a <span> and alter it's CSS on :checked

<div class="checkbox">
   <label>
      <input type="checkbox" name="packersOff" class="strikethrough" value="1">
      <span>sssssssss</span>
   </label>
</div>




.strikethrough:checked + span{
  text-decoration:line-through
}

Bootply

Here is a solution to put a strike through when your input is checked:

input[type=checkbox]:checked + label.strikethrough{
  text-decoration: line-through;
}

<div class="form-group ">
    <label for="inputName" class="col-md-1 control-label">select</label>  
    <div class="col-md-5">
        <div class="checkbox">
            <input type="checkbox" name="packersOff" id="packers" value="1"/>
            <label for="packers" class="strikethrough">sssssssss</label>
        </div>
     </div>
</div>

JSFIDDLE

With this solution when ever the checkbox is checked it will do something to the label. so you could make it bold or change its colour if you wanted.

.strikethrough:checked + .strikeThis {
  text-decoration: line-through
}

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet"/>
<div class="form-group ">
  <label for="inputName" class="col-md-1 control-label">select</label>
  <div class="col-md-5">
   
      <input name="packersOff" class="strikethrough" value="1" type="checkbox">
      <label for="packersOff" class="strikeThis">sssssssss</label>
    
  </div>
</div>