HTML

<div class="wrapper">
  <label class="checker">
    <input type="checkbox" name="something" value="true">
    <span class="check"></span>
    <span class="text">未チェック</span>
  </label>
</div>

CSS

/*-------------------------------------------------
チェックボックス
----------------------------------------------- */
/* チェックボックス周辺の見た目調整 */
.checker .check { display: inline-block; vertical-align: middle; }
.checker .text { display: inline-block; vertical-align: middle; max-width 80px; }
.checker input {
  display: none;
}
.checker .check {
  position: relative;
  display: inline-block;
  width: 18px;
  height: 18px;
  margin-right: 5px;
}
.checker .check::before {
  display: block;
  position: absolute;
  top: 2px;
  left: 0;
  width: 18px;
  height: 18px;
  border: 2px solid #ccc;
  content: "";
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  background: #fff;
}
.checker input:checked + .check::after {
  display: block;
  position: absolute;
  top: 5px;
  left: 3px;
  width: 16px;
  height: 8px;
  border-left: 3px solid #090;
  border-bottom: 3px solid #090;
  -webkit-transform: rotate(-45deg);
  -ms-transform: rotate(-45deg);
  transform: rotate(-45deg);
  content: "";
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}
.checker input:disabled + .check:before {
  background-color: #eee;
}
.checker input:checked:disabled + .check::after {
  border-left: 3px solid #aaa;
  border-bottom: 3px solid #aaa;
}