ant-design/components/collapse/style/index.less

@import '../../style/themes/default';
@import '../../style/mixins/index';

@collapse-prefix-cls: ~'@{ant-prefix}-collapse';

.collapse-close() {
  transform: rotate(0);
}
.collapse-open() {
  transform: rotate(90deg);
}

.@{collapse-prefix-cls} {
  .reset-component;
  background-color: @collapse-header-bg;
  border-radius: @border-radius-base;
  border: @border-width-base @border-style-base @border-color-base;
  border-bottom: 0;

  & > &-item {
    border-bottom: @border-width-base @border-style-base @border-color-base;

    &:last-child {
      &,
      & > .@{collapse-prefix-cls}-header {
        border-radius: 0 0 @border-radius-base @border-radius-base;
      }
    }

    > .@{collapse-prefix-cls}-header {
      line-height: 22px;
      padding: @collapse-header-padding;
      color: @heading-color;
      cursor: pointer;
      position: relative;
      transition: all 0.3s;

      .arrow {
        .iconfont-mixin();
        font-size: @font-size-sm;
        position: absolute;
        display: inline-block;
        line-height: 46px;
        vertical-align: top;
        top: 50%;
        transform: translateY(-50%);
        left: @padding-md;
        & svg {
          .collapse-close();
          transition: transform 0.24s;
        }
      }

      &:focus {
        outline: none;
      }
    }

    &.@{collapse-prefix-cls}-no-arrow {
      > .@{collapse-prefix-cls}-header {
        padding-left: 12px;
      }
    }
  }

  &-anim-active {
    transition: height 0.2s @ease-out;
  }

  &-content {
    overflow: hidden;
    color: @text-color;
    background-color: @collapse-content-bg;
    border-top: @border-width-base @border-style-base @border-color-base;

    & > &-box {
      padding: @collapse-content-padding;
    }

    &-inactive {
      display: none;
    }
  }

  &-item:last-child {
    > .@{collapse-prefix-cls}-content {
      border-radius: 0 0 @border-radius-base @border-radius-base;
    }
  }

  & > &-item > &-header[aria-expanded='true'] {
    .anticon-right svg {
      .collapse-open();
    }
  }

  &-borderless {
    background-color: @component-background;
    border: 0;
  }

  &-borderless > &-item {
    border-bottom: 1px solid @border-color-base;
  }

  &-borderless > &-item:last-child,
  &-borderless > &-item:last-child &-header {
    border-radius: 0;
  }

  &-borderless > &-item > &-content {
    background-color: transparent;
    border-top: 0;
  }

  &-borderless > &-item > &-content > &-content-box {
    padding-top: 4px;
  }

  & &-item-disabled > &-header {
    &,
    & > .arrow {
      cursor: not-allowed;
      color: @disabled-color;
    }
  }
}