If you have the option to modify your HTML code, I recommend using pseudo-elements to design custom checkboxes.
html
<div class="checkboxFour">
<input type="checkbox" value="1" id="checkboxFourInput" name="" data-toggle="modal" data-target="#myModal" />
<label for="checkboxFourInput">custom label</label>
</div>
css
input[type=checkbox] {
visibility: hidden;
}
. checkboxFour {
width: 10px;
height: 10px;
background: #ddd;
margin: 20px 90px;
border-radius: 100%;
position: relative;
box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.5);
}
.checkboxFour label:before {
content: "";
display: inline-block;
width: 8px;
height: 8px;
margin-right: 3px;
border-radius: 0;
transition: all .5s ease;
cursor: pointer;
z-index: 1;
background: #333;
box-shadow: inset 0px 1px 3px rgba(0, 0, 0, 0.5);
}
.checkboxFour input[type=checkbox]:checked + label:before {
background: #26ca28;
}
#boxlabel {
vertical-alignment: middle;
}
View the Jsfiddle