/* ==================== labs-join 主容器 ==================== */
.labs-join {
    clear: both;
    overflow: visible;
    margin: 48px auto;
    padding: 0 30px;
    display: flex;
    gap: 60px;
    font-family: DM Sans, DM Sans;
}

/* ==================== 左侧导航区域 ==================== */
.labsjoin-nav {
    width: 307px;
    background: #9B2742;
    padding: 0;
    position: relative;
    overflow: visible;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.labsjoin-nav ul {
    display: flex;
    flex-direction: column;
    width: 100%;
    gap: 10px;
}

/* 导航项基础样式 */
.labsjoin-nav ul li {
    color: #fff;
    font-size: 19px;
    transition: all .3s ease;
    position: relative;
    list-style: none;
    width: 100%;
    box-sizing: border-box;
    padding: 60px 87px;
    cursor: pointer;
}

/* 导航项悬停效果 */
.labsjoin-nav ul li:hover {
    color: #646464;
    background: #fff;
    transform: translateX(20px);
    box-shadow: 0 4px 4px rgba(0, 0, 0, .25);
}

/* 非折叠式导航项（校友简介、校友资金） */
.accordions-items {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
}

/* ==================== 折叠式导航项 ==================== */
/* 折叠项标题区域 */
.accordions-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 15px 0;
    cursor: pointer;
    transition: background-color 0.3s ease;
    position: relative;
    width: 100%;
    box-sizing: border-box;
}

/* 折叠项激活状态 */
.accordions-item.active .accordions-header {
    background-color: #fff;
    color: #646464;
}

/* 折叠项标题文本 */
.accordions-title {
    flex: 1;
    font-family: 'Times New Roman', Times, serif;
    font-size: 18px;
    font-weight: 400;
    padding-left: 30px;
    text-align: left;
}

/* 折叠项图标 */
.accordions-icon {
    width: 0;
    height: 0;
    border-top: 15px solid transparent;
    border-bottom: 15px solid transparent;
    border-left: 20px solid #9E0D30;
    transition: all 0.3s ease;
}

.accordions-item.active .accordions-icon {
    border-left-color: #fff;
}

/* ==================== 折叠项开关按钮 ==================== */
.accordions-toggle {
    width: 27px;
    height: 27px;
    color: #fff;
    background: transparent;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-left: auto;
    position: relative;
}


.accordions-toggle::before,
.accordions-toggle::after {
    content: '';
    position: absolute;
    background: currentColor;
    transition: all 0.3s ease;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.accordions-toggle::before {   /* 横线 */
    width: 10px;
    height: 2px;
}

.accordions-toggle::after {    /* 竖线 */
    width: 2px;
    height: 10px;
}

/* 激活状态：旋转45度并变为灰色 */
.accordions-item.active .accordions-toggle {
    color: #ccc;
    transform: rotate(45deg);
}

/* ==================== 折叠内容区域 ==================== */
.accordions-content {
    display: none;
    background-color: #fff;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

/* 激活时显示内容 */
.accordions-item.active .accordions-content {
    display: block;
    animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

/* ==================== 年份列表 ==================== */

.accordions-content .aluminiyear-item {
    position: relative;
    padding: 10px 0;
    padding-left: 40px;
    padding-right: 20px;
    font-size: 16px;
    color: #666;
    cursor: pointer;
    border-bottom: 1px dotted #ddd;
}

.accordions-content .aluminiyear-item:last-child {
    border-bottom: none;
}

/* 当前选中年份 */
.accordions-content .aluminiyear-item.current {
    color: #9B2742;
    font-weight: bold;
}

/* ==================== 右侧内容区域 ==================== */
.labsjoin-content {
    flex: 1;
    font: 400 14px/1.3 "Inter", sans-serif;
    color: #000;
}

/* 内容区域标题 */
.labsjoin-content h2 {
    margin-bottom: 60px;
    font-size: 23px;
    text-align: center;
    border-bottom: 2px dashed #949494;
    padding-bottom: 60px;
}

/* 内容区域段落 */
.labsjoin-content p {
    padding-top: 40px;
    text-align: justify;
    text-indent: 2em;
}

/* 图片行 */
.labsjoin-img {
    width: 100%;
    height: 270px;
    margin-top: 40px;
    padding-left: 360px;
    display: flex;
    gap: 60px;
}

/* ==================== 校友列表 ==================== */
.alumni-list {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

/* 年级和班级部分标题 */
.grade-section,
.class-section {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
}

.section-title {
    font-size: 17px;
    margin-right: 15px;
    font-weight: 400;
    color: #000;
}

.section-title .section-tangle {
    display: inline-block;
    margin-right: 5px;
    border: 4px solid transparent;
    border-left: 6px solid #9B2742;
}

/* 年级、班级、学生项 */
.grade-item,
.class-item,
.student-item {
    margin-right: 20px;
    color: #4c4c4c;
    cursor: pointer;
    transition: color .3s;
}

/* 悬停效果 */
.grade-item:hover,
.class-item:hover,
.student-item:hover {
    color: #9B2742;
}

/* 年级激活状态 */
.grade-item.active {
    color: #9B2742;
    font-weight: bold;
    position: relative;
}

.grade-item.active::after {
    content: "";
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: #9B2742;
}

/* 班级和学生列表容器 */
.class-items,
.student-names {
    display: none;
    flex-wrap: wrap;
    gap: 80px;
}

/* 激活状态显示 */
.class-items.active,
.student-names.active {
    display: flex;
    animation: fadeInSlide 0.3s ease;
}

/* 学生列表特定样式 */
.student-names {
    margin-top: 20px;
    line-height: 1.8;
}

/* 列表展开动画 */
@keyframes fadeInSlide {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ==================== 虚线分隔线 ==================== */
.alumni-list .dotted-line {
    height: 1px;
    margin: 20px 0;
    background: repeating-linear-gradient(to right,
            #ccc 0 5px,
            transparent 5px 10px);
    position: relative;
}

.alumni-list .dotted-line::before,
.alumni-list .dotted-line::after {
    content: "";
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 4px;
    height: 4px;
    border-radius: 50%;
    background: #ccc;
}

.alumni-list .dotted-line::before {
    left: 0;
}

.alumni-list .dotted-line::after {
    right: 0;
}