iview/src/styles/components/collapse.less

@collapse-prefix-cls: ~"@{css-prefix}collapse";

.@{collapse-prefix-cls}{
    background-color: @background-color-base;
    border-radius: 3px;
    border: 1px solid @border-color-base;

    &-simple{
        border-left: none;
        border-right: none;
        background-color: #fff;
    }

    & > &-item{
        border-top: 1px solid @border-color-base;
        &:first-child {
            border-top: 0;
        }

        > .@{collapse-prefix-cls}-header{
            height: 38px;
            line-height: 38px;
            padding-left: 16px;
            color: #666;
            cursor: pointer;
            position: relative;
            border-bottom: 1px solid transparent;
            transition: all @transition-time @ease-in-out;

            > i{
                transition: transform @transition-time @ease-in-out;
                margin-right: 14px;
            }
        }
    }
    &  > &-item&-item-active > &-header{
        border-bottom: 1px solid @border-color-base;
    }
    &-simple > &-item&-item-active > &-header{
        border-bottom: 1px solid transparent;
    }
    &  > &-item&-item-active > &-header > i{
        transform: rotate(90deg);
    }

    &-content{
        //display: none;
        //overflow: hidden;
        color: @text-color;
        padding: 0 16px;
        background-color: #fff;

        & > &-box {
            padding-top: 16px;
            padding-bottom: 16px;
        }
    }
    &-simple > &-item > &-content > &-content-box{
        padding-top: 0;
    }
    &-item-active > &-content{
        //display: block;
    }
    &-item:last-child {
        > .@{collapse-prefix-cls}-content {
            border-radius: 0 0 3px 3px;
        }
    }
}