message: refactor: collapse use css var
diff: +@import '../../core-css/index.scss';
  +
  .hi-collapse {
  text-align: left;
  border-bottom: 0;
  - border-radius: 3px;
  - font-size: 14px;
  + font-size: $font-size-normal;
  .collapse-item {
  - border-bottom: 1px solid #d8d8d8;
  + border-bottom: 1px solid use-color('gray-30');
  &__head {
  display: flex;
  align-items: center;
  - background-color: #fff;
  + background-color: use-color('white');
  padding: 12px 0 12px 16px;
  color: rgba(0, 0, 0, 0.85);
  cursor: pointer;
  color: rgba(0, 0, 0, 0.65);
  overflow: hidden;
  box-sizing: border-box;
  - background-color: #fbfbfb;
  + background-color: use-color('gray-10');
  }
  &--show {
  &--disabled {
  .collapse-item__head {
  cursor: not-allowed;
  - color: #ccc;
  + color: use-color('gray-50');
  }
  }
  }
  &__simple {
  .collapse-item {
  .head {
  - background-color: #fff;
  + background-color: use-color('white');
  }
  }
  }
  