/* ==============  Reset & base  ============== */
/* 全站平滑滚动，用于 Back to top 按钮 */
html {
  scroll-behavior: smooth;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial,
               "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  line-height: 1.55;
  color: #1c1c1c;
  background: #ffffff;
  overflow-wrap: break-word;
  word-wrap: break-word;
}

/* ============== Theme tokens ============== */
:root{
  --moam-purple: #4b0082;
  --moam-purple-700:#3f0070;
  --moam-purple-100:#efe6f7;
  --moam-black:#0f0f0f;
  --moam-grey:#666;
  --container: 1200px;
}

/* ============== Utilities ============== */
.container{
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 20px;
}

/* 跳转主内容的无障碍链接 */
.skip-link{
  position: absolute; left: -9999px; top: auto; width:1px; height:1px; overflow:hidden;
}
.skip-link:focus{
  left: 12px; top: 12px; width: auto; height: auto;
  background:#fff; color:#000; padding:10px 12px; border-radius:6px; z-index:9999;
}

/* ============== Team grid（原来的三列布局） ============== */
.team-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}
.team-item { width: 100%; }

@media (max-width: 992px) {
  .team-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .team-grid { grid-template-columns: 1fr; }
}


/* =========================================================
   Header: logo + 标题 + 右上学校 logo
   ========================================================= */
.site-header{
  background:#fff;
  border-bottom:4px solid var(--moam-purple);
}

/* 顶部横条：左右两边对齐 */
.site-header .header-bar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap: 24px;

  /* ↓ 减小上下 padding，抵消 logo 放大带来的高度 */
  padding: 4px 0 2px;
}

/* 左侧：logo + 标题 */
.brand-left{
  display:flex;
  align-items:center;
  gap: 10px;

  /* 不再强行 56px，稍微小一点，让整体更紧凑 */
  min-height: 48px;
}

/* 左侧 MoAM logo（略放大一点） */
.brand-left__logo img{
  display:block;
  height:64px;      /* 之前 54/60 左右，现在稍微大一点 */
  width:auto;
}

.brand-left__text{
  line-height:1.1;
}

/* 桌面端完整主标题（第一行） */
.brand-title--full{
  margin:0;
  font-size:26px;
  font-weight:800;
  letter-spacing:.01em;
  color: var(--moam-purple);
}

/* 第二行：RESEARCH GROUP – 高亮 + 可点击 */
.brand-subtitle--full{
  margin:2px 0 0 2px;
  font-size:16px;
  font-weight:900;
  text-transform:uppercase;
  letter-spacing:.25em;
  color:#e6007e;
}

/* 通用标题类（别处用到也不难看） */
.brand-title{
  margin:0 0 4px;
  font-size:24px;
  font-weight:800;
  color: var(--moam-purple);
}
.brand-subtitle{
  margin:0;
  font-size:14px;
  color:#666;
}

/* 手机端简短标题，默认隐藏，小屏再显示 */
.brand-title-short{
  display:none;
  margin:0;
  font-size:20px;
  font-weight:800;
  letter-spacing:.06em;
  color:var(--moam-purple);
}

/* 右上 Loughborough logo：比左边略大一点，但控制高度 */
.brand-right img{
  display:block;
  height:84px;     /* ★ 关键：比左 logo 大，但不会把 header 拉得很夸张 */
  width:auto;
}

/* 中等屏幕稍微缩放 */
@media (max-width: 900px){
  .brand-left__logo img{ height:52px; }
  .brand-right img{ height:70px; }
  .brand-title--full{ font-size:22px; }
}

/* 小屏：方案 C — 左边 MoAM • RG，右边 Loughborough，同一行缩小 */
@media (max-width: 720px){
  .site-header .header-bar{
    display: grid;
    grid-template-columns: 1fr auto;   /* 左 1fr，右自动宽度 */
    align-items: center;
    gap: 8px;
    padding: 6px 12px;                 /* 稍微紧凑一点 */
  }

  .brand-left{
    min-height: auto;
  }

  /* 左侧 MoAM logo 缩小 */
  .brand-left__logo img{
    height: 40px;
  }

  /* 右侧 Loughborough logo 更小一点 */
  .brand-right img{
    height: 32px;
  }

  /* 小屏：隐藏完整长标题，只保留 MoAM • RG 简写 */
  .brand-title--full,
  .brand-subtitle--full{
    display: none;
  }

  .brand-title-short{
    display: block;
    font-size: 1.2rem;
    font-weight: 800;
    letter-spacing: .06em;
  }
}



/* =========================================================
   Top navigation + mobile hamburger
   ========================================================= */
.main-nav{
  background:#111;
  border-top:4px solid var(--moam-purple);
  border-bottom:1px solid #222;
}

/* 让 nav 里面也是左右结构：左边汉堡 + 右边菜单 */
.main-nav .nav-inner{
  display:flex;
  align-items:center;
  justify-content:center;
}

/* PC 端菜单 */
/* 顶部导航条（PC 布局） */
.nav-list{
  display:flex;
  gap: 28px;
  list-style:none;
  padding:10px 0;
  margin:0;
}

/* 默认就有 3px 透明下边框 → 保证高度不变 */
.nav-list a{
  color:#f2f2f2;
  text-decoration:none;
  font-weight:600;
  letter-spacing:.02em;
  padding:8px 2px;
  display:inline-block;

  border-bottom:3px solid transparent;          /* ★ 预留空间 */
  transition:
    transform .15s ease,
    border-color .15s ease,
    color .15s ease;                             /* ★ 动画只作用在文字/边框 */
}

/* 选中 / 悬停：只改边框颜色 + 轻微上跳 */
.nav-list li.active a,
.nav-list a:hover,
.nav-list a:focus{
  color:#fff;
  border-bottom-color: #e6007e;       /* 不再新建 border，只改颜色 */
  transform: translateY(-2px);                   /* ★ 文字往上跳一点 */
}


/* Admin 按钮 */
.btn-admin{
  background:#e6007e;
  color:#fff !important;

  /* ↑ 把点击区域再加大一点 */
  padding:8px 22px;        /* 之前是 6px 18px */
  border-radius:999px;

  font-weight:600;
  font-size:15px;          /* 字再略微放大一点 */
  line-height:1.2;

  display:inline-flex;
  align-items:center;
  justify-content:center;

  /* 让它跟前面的菜单拉开一点距离 */
  margin-left:12px;
}

.btn-admin:hover{
  background:#6d28d9;
  text-decoration:none;
}

/* 汉堡菜单：大屏幕隐藏 */
.nav-toggle{
  display:none;
  background:none;
  border:0;
  padding:4px 8px;
  cursor:pointer;
}
.nav-toggle:focus-visible{
  outline:2px solid #fff;
  outline-offset:2px;
}
.nav-toggle__bar{
  display:block;
  width:22px;
  height:2px;
  background:#f5f5f5;
  margin:4px 0;
  transition:transform .2s ease, opacity .2s ease;
}

/* 展开状态：变 X */
.nav-toggle--open .nav-toggle__bar:nth-child(1){
  transform:translateY(6px) rotate(45deg);
}
.nav-toggle--open .nav-toggle__bar:nth-child(2){
  opacity:0;
}
.nav-toggle--open .nav-toggle__bar:nth-child(3){
  transform:translateY(-6px) rotate(-45deg);
}

/* 中屏 nav 略紧凑一点 */
@media (max-width: 900px){
  .nav-list{ gap:18px; flex-wrap:wrap; }
}

/* 手机端 nav：汉堡 + 下拉菜单 */
@media (max-width: 720px){

  .nav-toggle{
    display:inline-flex;
    flex-direction:column;
    justify-content:center;
    margin-right:8px;
  }

  .main-nav .nav-inner{
    position:relative;
    justify-content:space-between;   /* ★ 小屏再改回 space-between */
  }

  .main-nav .nav-list{
    display:none;
    position:absolute;
    left:0;
    top:100%;
    width:100%;
    padding:8px 16px 12px;
    margin:0;
    background:#111;
    flex-direction:column;
    gap:6px;
    box-shadow:0 4px 12px rgba(0,0,0,.6);
    z-index:20;
  }

  .main-nav .nav-list.nav-list--open{
    display:flex;
  }

  .main-nav .nav-list a{
    padding:6px 0;
  }
}


/* 如果你有 user 下拉菜单（nav-has-user），维持之前的样式 */
.nav-has-user {
  position: relative;
}
.nav-has-user .user-dropdown {
  position: absolute;
  top: 52px;
  right: 0;
  background: #fff;
  min-width: 160px;
  border: 1px solid #ddd;
  z-index: 999;
  display: none;
}
.nav-has-user:hover .user-dropdown {
  display:block;
}
.nav-has-user .user-dropdown a:hover {
  background:#f3f3f3;
}

/* =========================================================
   Hero 区 / Banner
   ========================================================= */
.hero{
  background: url("images/hero-sem.jpg") center/cover no-repeat;
  position:relative;
  border-bottom: 6px solid var(--moam-purple);
}
.hero::after{
  content:""; position:absolute; inset:0; background: rgba(0,0,0,.35);
}
.hero .hero-inner{
  position:relative; z-index:1;
  padding: 68px 0;
  color: #fff;
}
.hero-title{
  margin:0 0 6px; font-size: 38px; font-weight: 800;
  text-shadow: 0 2px 8px rgba(0,0,0,.35);
}
.hero-subtitle{
  margin:0; font-size: 18px; font-weight:600; opacity:.95;
}

/* 轮播 banner（你原来的那套） */
.banner{
  position: relative;
  border-bottom: 6px solid var(--moam-purple);
  overflow: hidden;
}
.banner__slides{
  position: relative;
  height: 320px;
}
.banner__slide{
  position: absolute; inset: 0;
  background-size: cover;
  background-position: center;
  opacity: 0;
  transition: opacity 700ms ease;
  z-index: 0;
}
.banner__slide.is-active{
  opacity: 1;
  z-index: 1;
}
.banner::after{
  content:""; position:absolute; inset:0;
  background: linear-gradient(to bottom, rgba(0,0,0,.25), rgba(0,0,0,.35));
  pointer-events:none;
}
.banner__text{
  position:absolute; left:24px; right:24px; bottom:18px;
  z-index:2; color:#fff;
  text-shadow: 0 2px 8px rgba(0,0,0,.35);
}
.banner__title{ margin:0 0 4px; font-size:30px; font-weight:900; }
.banner__subtitle{ margin:0; font-size:16px; font-weight:600; opacity:.95; }

.banner__ctrl{
  position:absolute; top:50%; transform:translateY(-50%);
  z-index:3; width:40px; height:40px; border-radius:50%;
  border:none; cursor:pointer; font-size:24px; line-height:40px;
  color:#fff; background: rgba(0,0,0,.35);
}
.banner__ctrl:hover{ background: rgba(0,0,0,.5); }
.banner__ctrl--prev{ left:10px; }
.banner__ctrl--next{ right:10px; }

.banner__dots{
  position:absolute; left:24px; bottom:16px; z-index:3;
  display:flex; gap:8px;
}
.banner__dots button{
  width:10px; height:10px; border-radius:50%;
  border:0; background: rgba(255,255,255,.55); cursor:pointer;
}
.banner__dots button.is-active{ background:#fff; }

/* Hero / Banner 在小屏略缩 */
@media (max-width:900px){
  .hero .hero-inner{ padding: 44px 0; }
  .hero-title{ font-size: 30px; }
  .hero-subtitle{ font-size: 16px; }

  .banner__slides{ height:240px; }
  .banner__title{ font-size:24px; }
  .banner__subtitle{ font-size:14px; }
}

/* =========================================================
   Main 两栏布局（左正文 + 右 News）
   ========================================================= */
.site-main{
  padding: 42px 0 56px;
  background:#fff;
}
.grid{
  display:grid;
  grid-template-columns: 2fr 1fr;
  gap: 36px;
}

/* 左侧正文 */
.page-title{
  color: var(--moam-purple);
  font-size: 34px;
  margin: 0 0 14px;
  font-weight: 900;
}
.content p{
  color:#2a2a2a;
  margin: 0 0 14px;
}
.content h2{
  margin: 26px 0 10px;
  font-size: 22px;
  color:#1a1a1a;
}
.bullet-list{
  padding-left: 20px;
  margin: 0;
}
.bullet-list li{ margin: 6px 0; }

/* 右侧 News */
.sidebar-title{
  font-size: 24px;
  color: var(--moam-purple);
  margin: 6px 0 14px;
  font-weight:900;
  border-bottom: 3px solid var(--moam-purple);
  display:inline-block;
  padding-bottom: 4px;
}
.news-card{
  background: var(--moam-purple);
  color:#fff;
  border-radius: 4px;
  padding: 16px 16px 18px;
  margin-bottom: 18px;
  position:relative;
  box-shadow: 0 2px 8px rgba(0,0,0,.15);
}
.news-date{
  display:block;
  font-size: 14px;
  opacity:.9;
  margin-bottom:6px;
}
.news-heading{
  margin: 0 0 8px;
  font-size: 17px;
  line-height:1.35;
}
.news-text{
  margin: 0;
  font-size: 15px;
}
.news-link{
  color:#fff;
  text-decoration: underline;
}
.news-link:hover,
.news-link:focus{
  text-decoration:none;
}

/* 中等屏幕两栏比例略改 */
@media (max-width: 1080px){
  .grid{ grid-template-columns: 1.5fr 1fr; }
}

/* 小屏：改为单栏 */
@media (max-width: 760px){
  .grid{ grid-template-columns: 1fr; }
}

/* =========================================================
   Footer
   ========================================================= */
.site-footer{
  background: #0d0d0d;
  color:#eee;
  border-top: 6px solid var(--moam-purple);
  font-size: 14px;
}
.footer-inner{
  display:grid;
  grid-template-columns: 2fr 1fr;
  gap: 24px;
  padding: 18px 0 22px;
}
.footer-left p{ margin: 6px 0; }
.footer-right{ text-align:right; }
.footer-right p{
  margin: 6px 0;
  color:#d7d7d7;
}
.footer-right a{ color:#fff; }
/* Footer 中的人名/邮箱不换行，保证一条一句 */
.footer-right .contact-name{
  white-space: nowrap;
}


/* Footer login 按钮化 */
.login-link{
  display: inline-block;
  padding: 10px 16px;
  background: #666;
  color: #fff;
  border-radius: 10px;
  border: 1px solid rgba(255,255,255,.12);
  font-weight: 700;
  letter-spacing: .2px;
  text-decoration: none;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.25);
  transition: transform .15s ease, box-shadow .15s ease, background .15s ease;
}
.login-link:hover,
.login-link:focus{
  background: var(--moam-purple-700);
  box-shadow: 0 4px 14px rgba(0,0,0,.3);
  transform: translateY(-1px);
  text-decoration:none;
}
.login-link:focus-visible{
  outline: 3px solid #fff;
  outline-offset: 2px;
}

/* Research Group 链接保持同风格 + 轻微下划线 */
.brand-subtitle-link{
  color: inherit;
  text-decoration:none;
  position:relative;
}
.brand-subtitle-link::after{
  content:"";
  position:absolute;
  left:0;
  bottom:-4px;
  width:100%;
  height:2px;
  background:#e6007e;
  opacity:.6;
}
.brand-subtitle-link:hover,
.brand-subtitle-link:focus{
  opacity:1;
}


/* Footer 小屏堆叠 */
@media (max-width: 760px){
  .footer-inner{
    grid-template-columns: 1fr;
    text-align:center;
  }
  .footer-right{ text-align:center; }
}

/* ★ 如果你不想暗色主题自动变黑，可以直接删掉这一段 */
@media (prefers-color-scheme: dark){
  .login-link{ border-color: rgba(255,255,255,.18); }
}

/* =========================
   悬浮“Back to top”按钮
   ========================= */

/* 默认（桌面端为主）样式 */
.back-to-top-float {
  position: fixed;
  right: 1.5rem;
  bottom: 2rem;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: 999px;
  background: rgba(75, 0, 130, 0.9);  /* 深紫，和站点主色协调 */
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  text-decoration: none;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.25);
  z-index: 50;

  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
  transition: opacity 0.25s ease, transform 0.25s ease, background 0.2s ease;
}

/* 通过 JS 添加这个 class 来控制显示/隐藏 */
.back-to-top-float--visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.back-to-top-float:hover {
  background: rgba(92, 36, 150, 1);
}

/* =========================
   Media Queries 自适应
   ========================= */

/* 中等屏幕及以下（平板 / 小笔记本）：按钮稍微小一点，贴边近一点 */
@media (max-width: 1024px) {
  .back-to-top-float {
    right: 1.2rem;
    bottom: 1.8rem;
    width: 2.4rem;
    height: 2.4rem;
    font-size: 1.25rem;
  }
}

/* 手机（竖屏，max-width 768）再小一点，避免遮挡内容 */
@media (max-width: 768px) {
  .back-to-top-float {
    right: 1rem;
    bottom: 1.5rem;
    width: 2.1rem;
    height: 2.1rem;
    font-size: 1.1rem;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.25);
  }
}

/* 超小屏（如老手机 / 特别窄的屏幕）进一步缩小一点 */
@media (max-width: 480px) {
  .back-to-top-float {
    right: 0.8rem;
    bottom: 1.2rem;
    width: 1.9rem;
    height: 1.9rem;
    font-size: 1rem;
  }
}