css多选框checkbox样式

源码：

<div class="container">
    <!-- TITLE -->
    <span class="title">
        css Material Design checkbox
    </span>
    <!-- CHECKBOXES -->
    <div class="checkbox">
        <input type="checkbox" id="checkbox1" class="checkbox__input" checked>
        <label for="checkbox1" class="checkbox__label">Checkbox 1</label>
    </div><br>
    <div class="checkbox">
        <input type="checkbox" id="checkbox2" class="checkbox__input">
        <label for="checkbox2" class="checkbox__label">Checkbox 2</label>
    </div><br>
    <div class="checkbox">
        <input type="checkbox" id="checkbox3" class="checkbox__input">
        <label for="checkbox3" class="checkbox__label">Checkbox 3</label>
    </div><br>
</div>

<style>
body, html {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Roboto, sans-serif;
  width: 100%;
  background: #fafafa;
  color: #757575;
}

*, *:before, *:after {
  box-sizing: inherit;
}

.container {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}

.title {
  display: block;
  margin: 0 0 20px;
  font-size: 24px;
  text-transform: uppercase;
}

.checkbox {
  display: inline-block;
  position: relative;
  margin: 0 0 10px;
  font-size: 16px;
  line-height: 24px;
}

.checkbox__input {
  position: absolute;
  top: 4px;
  left: 0;
  width: 16px;
  height: 16px;
  opacity: 0;
  z-index: 0;
}

.checkbox__label {
  display: block;
  padding: 0 0 0 24px;
  cursor: pointer;
}

.checkbox__label:before {
  content: '';
  position: absolute;
  top: 4px;
  left: 0;
  width: 16px;
  height: 16px;
  background-color: transparent;
  border: 2px solid rgba(0, 0, 0, 0.54);
  border-radius: 2px;
  z-index: 1;
  transition: all 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  transition-property: background-color, border-color;
}

.checkbox__label:after {
  content: '';
  position: absolute;
  top: 5px;
  left: 5px;
  width: 6px;
  height: 12px;
  border-bottom: 2px solid transparent;
  border-right: 2px solid transparent;
  transform: rotate(45deg);
  z-index: 2;
  transition: border-color 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

.checkbox__input:checked + .checkbox__label:before {
  background-color: #3f51b5;
  border-color: #3f51b5;
}

.checkbox__input:checked + .checkbox__label:after {
  border-color: #fff;
}

</style>

链接: https://www.fly63.com/course/33_1576