<div class="checks">
  <input type="checkbox" id="ex_chk"> 
  <label for="ex_chk">체크박스</label> 
</div>

<br />

<div class="checks small">
  <input type="checkbox" id="ex_chk2"> 
  <label for="ex_chk2">체크박스</label> 
</div>

<br />

<div class="checks etrans">
  <input type="checkbox" id="ex_chk3"> 
  <label for="ex_chk3">체크박스</label> 
</div>

<a href="http://webdir.tistory.com/433" target="_blank" class="where">posted in webdir</a> 

body {margin: 10px;}
.where {
  display: block;
  margin: 25px 15px;
  font-size: 11px;
  color: #000;
  text-decoration: none;
  font-family: verdana;
  font-style: italic;
}

.checks {position: relative;}

.checks input[type="checkbox"] {  /* 실제 체크박스는 화면에서 숨김 */
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip:rect(0,0,0,0);
  border: 0
}
.checks input[type="checkbox"] + label {
  display: inline-block;
  position: relative;
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
}
.checks input[type="checkbox"] + label:before {  /* 가짜 체크박스 */
  content: ' ';
  display: inline-block;
  width: 21px;  /* 체크박스의 너비를 지정 */
  height: 21px;  /* 체크박스의 높이를 지정 */
  line-height: 21px; /* 세로정렬을 위해 높이값과 일치 */
  margin: -2px 8px 0 0;
  text-align: center; 
  vertical-align: middle;
  background: #fafafa;
  border: 1px solid #cacece;
  border-radius : 3px;
  box-shadow: 0px 1px 2px rgba(0,0,0,0.05), inset 0px -15px 10px -12px rgba(0,0,0,0.05);
}
.checks input[type="checkbox"] + label:active:before,
.checks input[type="checkbox"]:checked + label:active:before {
  box-shadow: 0 1px 2px rgba(0,0,0,0.05), inset 0px 1px 3px rgba(0,0,0,0.1);
}

.checks input[type="checkbox"]:checked + label:before {  /* 체크박스를 체크했을때 */ 
  content: '\2714';  /* 체크표시 유니코드 사용 */
  color: #99a1a7;
  text-shadow: 1px 1px #fff;
  background: #e9ecee;
  border-color: #adb8c0;
  box-shadow: 0px 1px 2px rgba(0,0,0,0.05), inset 0px -15px 10px -12px rgba(0,0,0,0.05), inset 15px 10px -12px rgba(255,255,255,0.1);
}

.checks.small input[type="checkbox"] + label {
  font-size: 12px;
}

.checks.small input[type="checkbox"] + label:before {
  width: 17px;
  height: 17px;
  line-height: 17px;
  font-size: 11px;
}

.checks.etrans input[type="checkbox"] + label {
  padding-left: 30px;
}
.checks.etrans input[type="checkbox"] + label:before {
  position: absolute;
  left: 0;
  top: 0;
  margin-top: 0;
  opacity: .6;
  box-shadow: none;
  border-color: #6cc0e5;
  -webkit-transition: all .12s, border-color .08s;
  transition: all .12s, border-color .08s;
}

.checks.etrans input[type="checkbox"]:checked + label:before {
  position: absolute;
  content: "";
  width: 10px;
  top: -5px;
  left: 5px;
  border-radius: 0;
  opacity:1; 
  background: transparent;
  border-color:transparent #6cc0e5 #6cc0e5 transparent;
  border-top-color:transparent;
  border-left-color:transparent;
  -ms-transform:rotate(45deg);
  -webkit-transform:rotate(45deg);
  transform:rotate(45deg);
}

.no-csstransforms .checks.etrans input[type="checkbox"]:checked + label:before {
  /*content:"\2713";*/
  content: "\2714";
  top: 0;
  left: 0;
  width: 21px;
  line-height: 21px;
  color: #6cc0e5;
  text-align: center;
  border: 1px solid #6cc0e5;
}