HTML
<div class="checkbox"><p><input id="agree" type="checkbox" name="" value=""><label for="agree"テキスト</label></p></div>
CSS
.checkbox{
}
.checkbox input[type="checkbox"]{
display: none;
}
.checkbox label{
display: block;
position: relative;
padding-left: 70px;
}
.checkbox label:after{
content: "";
display: inline-block;
width: 55px;
height: 55px;
border: 2px solid #000000;
margin-right: 15px;
position: absolute;
left: 0px;
top: 50%;
transform: translate3d(0,-50%,0);
}
.checkbox input[type="checkbox"]:checked + label:before {
content: "";
position: absolute;
z-index: 1;
top: 15px;
left: 4px;
width: 55px;
height: 25px;
border: 7px solid #1a1363;
border-top-style: none;
border-right-style: none;
transform: rotate(-45deg) scale(1, 1);
}