<h1>flat form</h1>
<div class="container style1 subcontainer">
   <input type="checkbox" id="style1checkbox">
   <label for="style1checkbox"></label>
   <input type="checkbox" id="style1checkbox2">
   <label for="style1checkbox2"></label>
   <input type="checkbox" id="style1checkbox3">
   <label for="style1checkbox3"></label>
   <input type="checkbox" id="style1checkbox4">
   <label for="style1checkbox4"></label>
   <span>checkbox</span>
</div>
<div class="container style1">
   <input type="radio" id="style1radio1" name="style1radio1">
   <label for="style1radio1"></label>
   <input type="radio" id="style1radio2" name="style1radio1">
   <label for="style1radio2"></label>
   <input type="radio" id="style1radio3" name="style1radio1">
   <label for="style1radio3"></label>
   <input type="radio" id="style1radio4" name="style1radio1">
   <label for="style1radio4"></label>
   <span>radio</span>
</div>
<div class="container style2 subcontainer">
   <input type="checkbox" id="style2checkbox">
   <label for="style2checkbox"></label>
   <input type="checkbox" id="style2checkbox2">
   <label for="style2checkbox2"></label>
   <input type="checkbox" id="style2checkbox3">
   <label for="style2checkbox3"></label>
   <input type="checkbox" id="style2checkbox4">
   <label for="style2checkbox4"></label>
   <span>checkbox</span>
</div>
<div class="container style2">
   <input type="radio" id="style2radio1" name="style2radio1">
   <label for="style2radio1"></label>
   <input type="radio" id="style2radio2" name="style2radio1">
   <label for="style2radio2"></label>
   <input type="radio" id="style2radio3" name="style2radio1">
   <label for="style2radio3"></label>
   <input type="radio" id="style2radio4" name="style2radio1">
   <label for="style2radio4"></label>
   <span>radio</span>
</div>
<div class="container style3 subcontainer">
   <input type="checkbox" id="style3checkbox">
   <label for="style3checkbox"></label>
   <input type="checkbox" id="style3checkbox2">
   <label for="style3checkbox2"></label>
   <input type="checkbox" id="style3checkbox3">
   <label for="style3checkbox3"></label>
   <input type="checkbox" id="style3checkbox4">
   <label for="style3checkbox4"></label>
   <span>checkbox</span>
</div>
<div class="container style3">
   <input type="radio" id="style3radio1" name="style3radio1">
   <label for="style3radio1"></label>
   <input type="radio" id="style3radio2" name="style3radio1">
   <label for="style3radio2"></label>
   <input type="radio" id="style3radio3" name="style3radio1">
   <label for="style3radio3"></label>
   <input type="radio" id="style3radio4" name="style3radio1">
   <label for="style3radio4"></label>
   <span>radio</span>
</div>
<div class="container style4 subcontainer">
   <input type="checkbox" id="style4checkbox">
   <label for="style4checkbox"></label>
   <input type="checkbox" id="style4checkbox2">
   <label for="style4checkbox2"></label>
   <input type="checkbox" id="style4checkbox3">
   <label for="style4checkbox3"></label>
   <input type="checkbox" id="style4checkbox4">
   <label for="style4checkbox4"></label>
   <span>checkbox</span>
</div>
<div class="container style4">
   <input type="radio" id="style4radio1" name="style4radio1">
   <label for="style4radio1"></label>
   <input type="radio" id="style4radio2" name="style4radio1">
   <label for="style4radio2"></label>
   <input type="radio" id="style4radio3" name="style4radio1">
   <label for="style4radio3"></label>
   <input type="radio" id="style4radio4" name="style4radio1">
   <label for="style4radio4"></label>
   <span>radio</span>
</div>
<div class="container subcontainer">
  <input type="text" placeholder="textbox"/>
</div>
<div class="container subcontainer">
  <textarea name="textbox" placeholder="textarea"></textarea>
</div>
<div class="container">
  <select class="selectbox">
    <option>option 1</option>
    <option>option 2</option>
    <option>option 3</option>
    <option>option 4</option>
  </select>
</div>
<div class="container">
  <input type="submit" value="send">
</div>
@import url(https://fonts.googleapis.com/css?family=ABeeZee);

body {
  background:#2c3e50;
  padding:20px 0px;
  font-family: 'ABeeZee', sans-serif;
  font-size:15px;
}

h1 {
  text-align:center;
  color:#fff;
  font-size:25px;
  margin-bottom:20px;
}

@mixin box-sizing() {
  -webkit-box-sizing:border-box;
  -moz-box-sizing:border-box;
  -ms-box-sizing:border-box;
  -o-box-sizing:border-box;
  box-sizing:border-box;
}

.container {
  width:260px;
  margin:0 auto;
  border-bottom:4px solid #3498db;
  padding:15px 0px;
  @include box-sizing;
}

.subcontainer {
  border-width:2px;
  border-color:#34495e;
}

input {
  display:none;
  font-size:15px;
}

span {
  float:right;
  color:#ecf0f1;
}

.style1 {
  label {
    width:26px;
    height:15px;
    margin-bottom:-3px;
    margin-right:10px;
    background:transparent;
    cursor:pointer;
    position:relative;
    display:inline-block;
    &::before {
      content:"";
      width:26px;
      height:6px;
      background:#333;
      display:block;
      cursor:pointer;
      position:absolute;
      top:3px;
    }
    &::after {
      content:"";
      position:absolute;
      width:12px;
      height:12px;
      top:0px;
      left:1px;
      background:#e74c3c;
      border-radius:100%;
      z-index:1;
      -webkit-transition:300ms all;
      -moz-transition:300ms all;
      -ms-transition:300ms all;
      -o-transition:300ms all;
      transition:300ms all;
    }
  }
  input:checked + label::after {
    left:13px;
    background:#27ae60;
   }
}

.style2 {
  label {
    width:18px;
    height:18px;
    margin-bottom:-3px;
    margin-right:10px;
    background:#e74c3c;
    border-radius:3px;
    cursor:pointer;
    position:relative;
    display:inline-block;
    -webkit-transition:300ms all;
    -moz-transition:300ms all;
    -ms-transition:300ms all;
    -o-transition:300ms all;
    transition:300ms all;
    &::after {
      content:"";
      position:absolute;
      width:3px;
      height:11px;
      left:7px;
      top:1px;
      border-right:2px solid #fff;
      border-bottom:2px solid #fff;
      -webkit-transform:rotate(45deg);
      -moz-transform:rotate(45deg);
      -ms-transform:rotate(45deg);
      -o-transform:rotate(45deg);
      transform:rotate(45deg);
      opacity:0;
      -webkit-backface-visibility:hidden;
      z-index:1;
      -webkit-transition:300ms opacity;
      -moz-transition:300ms opacity;
      -ms-transition:300ms opacity;
      -o-transition:300ms opacity;
      transition:300ms opacity;
    }
  }
  input:checked + label {
    background:#27ae60;
  }
  input:checked + label::after {
    opacity:1;
  }
  input[type=radio] + label {
    border-radius:100%;
    &::after {
      left:6px;
      top:2px;
      height:10px;
    }
  }
}

.style3 {
  label {
    width:26px;
    height:16px;
    margin-bottom:-3px;
    margin-right:10px;
    background:#ecf0f1;
    border-radius:7px;
    cursor:pointer;
    position:relative;
    display:inline-block;
    &::before {
      content:"";
      width:24px;
      height:12px;
      background:#bdc3c7;
      display:block;
      cursor:pointer;
      position:absolute;
      top:2px;
      left:1px;
      border-radius:7px;
    }
    &::after {
      content:"";
      position:absolute;
      width:12px;
      height:12px;
      top:2px;
      left:1px;
      background:#e74c3c;
      border-radius:100%;
      z-index:1;
      -webkit-transition:300ms all;
      -moz-transition:300ms all;
      -ms-transition:300ms all;
      -o-transition:300ms all;
      transition:300ms all;
    }
  }
  input:checked + label::after {
    left:13px;
    background:#27ae60;
   }
}

.style4 {
  label {
    width:18px;
    height:18px;
    margin-bottom:-3px;
    margin-right:10px;
    background:#e74c3c;
    border-radius:3px;
    cursor:pointer;
    position:relative;
    display:inline-block;
    -webkit-transition:300ms all;
    -moz-transition:300ms all;
    -ms-transition:300ms all;
    -o-transition:300ms all;
    transition:300ms all;
    &::after {
      content:"";
      position:absolute;
      width:12px;
      height:12px;
      left:3px;
      top:3px;
      background:#c0392b;
      border-radius:3px;
      opacity:1;
      z-index:1;
      -webkit-transition:300ms all;
      -moz-transition:300ms all;
      -ms-transition:300ms all;
      -o-transition:300ms all;
      transition:300ms all;
    }
  }
  input:checked + label {
    background:#27ae60;
  }
  input:checked + label::after {
    opacity:1;
    background:#2ecc71;
  }
  input[type=radio] + label {
    border-radius:100%;
    &::after {
      border-radius:100%;
    }
  }
}

input[type=text],
input[type=email] {
  display:inline-block;
  border:none;
  background:#34495e;
  @include box-sizing;
  padding:8px;
  color:#ecf0f1;
  width:100%;
  &:focus {
    outline: none;
  }
  &::-webkit-input-placeholder {
    color:#999;
  }
  &:-moz-input-placeholder {
    color:#999;
  }
  &::-moz-placeholder {
    color:#999;
  }
  &:-ms-input-placeholder {
    color:#999;
  }
}

textarea {
  width:100%;
  max-width:100%;
  min-width:100%;
  min-height:80px;
  @include box-sizing;
  padding:8px;
  background:#34495e;
  border:none;
  color:#ecf0f1;
  font-size:15px;
  font-family: 'ABeeZee', sans-serif;
  &:focus {
    outline:none;
  }
  &::-webkit-input-placeholder {
    color:#999;
  }
  &:-moz-input-placeholder {
    color:#999;
    font-family: 'ABeeZee', sans-serif;
  }
  &::-moz-placeholder {
    color:#999;
    font-family: 'ABeeZee', sans-serif;
  }
  &:-ms-input-placeholder {
    color:#999;
  }
}

select.selectbox {display:none;}
dl.selectbox  {
  width:100%;
  cursor:pointer;
  position:relative;
  dt {
    width:100%;
    background:#34495e;
    @include box-sizing;
    color:#ecf0f1;
    padding:8px;
    position:relative;
    &::after {
      content:"";
      position:absolute;
      width:12px;
      height:12px;
      border-right:solid 1px #bdc3c7;
      border-bottom: solid 1px #bdc3c7;
      right:10px;
      top:6px;
      -webkit-transform:rotate(45deg);
      -moz-transform:rotate(45deg);
      -ms-transform:rotate(45deg);
      -o-transform:rotate(45deg);
      transform:rotate(45deg);
    }
  }
  dt.open::after {
    -webkit-transform:rotate(225deg);
    -moz-transform:rotate(225deg);
    -ms-transform:rotate(225deg);
    -o-transform:rotate(225deg);
    transform:rotate(225deg);
    top:12px;
  }
  dd {
    position:absolute;
    width:100%;
    z-index:10;
    visibility:hidden;
    opacity:0;
    -webkit-transition:300ms all;
    -moz-transition:300ms all;
    -ms-transition:300ms all;
    -o-transition:300ms all;
    transition:300ms all;
    &.open {
      visibility:visible;
      opacity:1;
    }
  }
  dd ul li {
    width:100%;
    background:#344956;
    @include box-sizing;
    color:#ecf0f1;
    padding:8px;
  }
}

input[type=submit] {
  display:block;
  @include box-sizing;
  border:none;
  -webkit-appearance:none;
  color:#ecf0f1;
  padding:8px;
  background:#34495e;
  width:100%;
  cursor:pointer;
  &:active,
  &:focus{
    outline:none;
  }
}
View Compiled
// Just for the selectbox

$(document).ready(function(){
  simpleSelect();
});

function simpleSelect() {
  "use strict";
  var selectHolder,
      selectClass;
  //Setup
  $('select').each(function() {
    selectClass = $(this).attr('class');
    selectHolder = '<dl class="simpleSelect '+selectClass+'">';
    selectHolder += '<dt>'+$('option', this).first().text()+'</dt><dd><ul>';
    $('option', this).each(function() {
      selectHolder += '<li data="'+$(this).val()+'">'+$(this).text()+'</li>';
    });
    selectHolder += '</ul></dd></dl>';
    $(this).after(selectHolder);
    $('.'+selectClass).wrapAll('<div class="selectContainer"></div>');
  });
  
  //Clicks
  $('.simpleSelect dd ul li').on("click",function(){
    $(this).parents().eq(3).find('select').val($(this).attr('data'));
  });
  
  $('.simpleSelect dt').on("click",function() {
    if($(this).next('dd').hasClass("open")){
      $(this).removeClass("open").next('dd').removeClass("open");
    }
    else {
      $(this).addClass("open").next('dd').addClass("open");
    }
  });
  
  $('.simpleSelect dd ul li').on("click",function() {
    $(this).parents().eq(1).removeClass("open");
    $(this).parents().eq(2).find('dt').removeClass("open");
    $(this).parents().eq(4).find('dt').text($(this).text());
  });
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js