/* =========================================================
   MBNRG — Mobile Broadband Network Research Group
   Stylesheet
   ========================================================= */

:root{
  --ink:        #0E1B2C;
  --ink-soft:   #1B2A3F;
  --paper:      #F4F6F5;
  --paper-raise:#FFFFFF;
  --line:       #E1E6E7;
  --text:       #1B2430;
  --text-soft:  #4B5768;
  --text-mute:  #8993A4;
  --signal:     #0F9C9C;
  --signal-dark:#0B7A7A;
  --signal-tint:#E4F5F4;
  --pulse:      #E7592B;
  --radius:     10px;
  --maxw:       1180px;
  --font-display: 'Space Grotesk', 'Segoe UI', sans-serif;
  --font-body:  'Inter', 'Segoe UI', sans-serif;
  --font-mono:  'JetBrains Mono', ui-monospace, monospace;
}

*{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  font-family:var(--font-body);
  color:var(--text);
  background:var(--paper);
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
img{ max-width:100%; display:block; }
a{ color:var(--signal-dark); text-decoration:none; }
a:hover{ color:var(--pulse); }
ul{ margin:0; padding:0; list-style:none; }
h1,h2,h3,h4{
  font-family:var(--font-display);
  color:var(--ink);
  line-height:1.15;
  margin:0 0 .5em 0;
  letter-spacing:-0.01em;
}
p{ margin:0 0 1em 0; }
.wrap{ max-width:var(--maxw); margin:0 auto; padding:0 28px; }
.eyebrow{
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  text-transform:uppercase;
  color:var(--signal-dark);
  display:inline-flex;
  align-items:center;
  gap:8px;
  margin-bottom:12px;
}
.eyebrow::before{
  content:"";
  width:18px; height:1px;
  background:var(--signal-dark);
  display:inline-block;
}
:focus-visible{ outline:2px solid var(--signal); outline-offset:3px; }

/* ---------- Top identity bar ---------- */
.topbar{
  background:var(--ink);
  color:#B9C4D3;
  font-family:var(--font-mono);
  font-size:12px;
}
.topbar .wrap{
  display:flex; justify-content:space-between; align-items:center;
  padding:7px 28px;
}
.topbar a{ color:#B9C4D3; }
.topbar a:hover{ color:#fff; }

/* ---------- Header ---------- */
.site-header{
  background:var(--paper-raise);
  border-bottom:1px solid var(--line);
  position:sticky; top:0; z-index:50;
}
.header-inner{
  display:flex; align-items:center; justify-content:space-between;
  padding:16px 28px;
  max-width:var(--maxw); margin:0 auto;
  gap:20px;
}
.brand{ display:flex; align-items:center; gap:14px; }
.brand-mark{
  width:44px; height:44px; border-radius:50%;
  background:var(--ink);
  display:flex; align-items:center; justify-content:center;
  flex-shrink:0;
}
.brand-mark svg{ width:26px; height:26px; }
.brand-text h1{
  font-size:17px; margin:0; letter-spacing:-.01em;
}
.brand-text span{
  display:block; font-size:12px; color:var(--text-mute); font-family:var(--font-mono);
}
nav.main-nav ul{ display:flex; gap:2px; }
nav.main-nav a{
  color:var(--text-soft);
  font-weight:600;
  font-size:14.5px;
  padding:10px 14px;
  border-radius:7px;
  transition:background .15s, color .15s;
}
nav.main-nav a:hover{ background:var(--signal-tint); color:var(--signal-dark); }
nav.main-nav a.active{ color:var(--signal-dark); background:var(--signal-tint); }
.nav-toggle{ display:none; background:none; border:none; cursor:pointer; padding:8px; }
.nav-toggle span, .nav-toggle span::before, .nav-toggle span::after{
  content:""; display:block; width:24px; height:2px; background:var(--ink); position:relative; transition:.2s;
}
.nav-toggle span::before{ position:absolute; top:-7px; }
.nav-toggle span::after{ position:absolute; top:7px; }

@media (max-width:900px){
  nav.main-nav{
    position:absolute; top:100%; left:0; right:0;
    background:var(--paper-raise); border-bottom:1px solid var(--line);
    display:none; padding:10px 20px 18px;
  }
  nav.main-nav.open{ display:block; }
  nav.main-nav ul{ flex-direction:column; }
  .nav-toggle{ display:block; }
}

/* ---------- Hero ---------- */
.hero{
  position:relative;
  background:var(--ink);
  color:#fff;
  overflow:hidden;
  padding:76px 0 84px;
}
.hero-rings{
  position:absolute; right:-120px; top:50%; transform:translateY(-50%);
  width:640px; height:640px; pointer-events:none;
}
.hero-rings circle{
  fill:none; stroke:var(--signal); stroke-opacity:.35;
}
.hero-grid{
  position:absolute; inset:0; opacity:.06;
  background-image:
    linear-gradient(#8FF 1px, transparent 1px),
    linear-gradient(90deg, #8FF 1px, transparent 1px);
  background-size:40px 40px;
}
.hero .wrap{ position:relative; display:grid; grid-template-columns:1.15fr .85fr; gap:40px; align-items:center; }
.hero h2{
  color:#fff; font-size:clamp(30px,4.2vw,48px); margin-bottom:18px; max-width:620px;
}
.hero h2 em{ color:var(--signal); font-style:normal; }
.hero p.lead{
  color:#C4CEDA; font-size:17px; max-width:540px; margin-bottom:28px;
}
.hero-cta{ display:flex; gap:12px; flex-wrap:wrap; }
.btn{
  display:inline-flex; align-items:center; gap:8px;
  font-weight:700; font-size:14.5px;
  padding:12px 20px; border-radius:8px;
  transition:transform .15s, background .15s, color .15s;
  border:1px solid transparent;
}
.btn-primary{ background:var(--signal); color:#03211F !important; }
.btn-primary:hover{ background:#12b3b3; transform:translateY(-1px); }
.btn-ghost{ border-color:rgba(255,255,255,.35); color:#fff !important; }
.btn-ghost:hover{ background:rgba(255,255,255,.08); }
.btn-outline{ border-color:var(--line); color:var(--ink) !important; }
.btn-outline:hover{ background:var(--signal-tint); border-color:var(--signal); }

.director-card{
  background:rgba(255,255,255,.05);
  border:1px solid rgba(255,255,255,.14);
  border-radius:14px;
  padding:22px;
  backdrop-filter:blur(2px);
}
.director-card .photo{
  width:68px; height:68px; border-radius:50%; overflow:hidden;
  border:2px solid var(--signal); margin-bottom:14px;
}
.director-card .photo img{ width:100%; height:100%; object-fit:cover; }
.director-card h3{ color:#fff; font-size:18px; margin-bottom:2px; }
.director-card .role{ color:var(--signal); font-family:var(--font-mono); font-size:12px; margin-bottom:12px; }
.director-card p{ color:#B9C4D3; font-size:14px; margin-bottom:4px; }
.director-card a.link{ color:var(--signal); font-weight:700; font-size:13px; }

/* ---------- Stats strip ---------- */
.stats-strip{
  background:var(--paper-raise);
  border-bottom:1px solid var(--line);
}
.stats-strip .wrap{
  display:grid; grid-template-columns:repeat(4,1fr);
  padding:26px 28px;
}
.stat{ text-align:center; padding:0 10px; border-left:1px solid var(--line); }
.stat:first-child{ border-left:none; }
.stat .num{
  font-family:var(--font-display); font-size:32px; color:var(--ink); font-weight:700;
}
.stat .num span{ color:var(--signal-dark); }
.stat .label{ font-size:12.5px; color:var(--text-mute); font-family:var(--font-mono); text-transform:uppercase; letter-spacing:.06em; margin-top:2px; }
@media (max-width:760px){
  .stats-strip .wrap{ grid-template-columns:repeat(2,1fr); row-gap:20px; }
  .stat:nth-child(3){ border-left:none; }
}

/* ---------- Section shell ---------- */
section.block{ padding:64px 0; }
section.block.alt{ background:var(--paper-raise); border-top:1px solid var(--line); border-bottom:1px solid var(--line); }
.section-head{ max-width:680px; margin-bottom:36px; }
.section-head h2{ font-size:28px; }
.section-head p{ color:var(--text-soft); font-size:15.5px; }

/* ---------- Research cards ---------- */
.research-grid{ display:grid; grid-template-columns:repeat(3,1fr); gap:22px; }
.research-card{
  background:var(--paper-raise);
  border:1px solid var(--line);
  border-radius:var(--radius);
  padding:26px;
  transition:border-color .15s, transform .15s;
}
.research-card:hover{ border-color:var(--signal); transform:translateY(-3px); }
.research-card .icon{
  width:46px; height:46px; border-radius:9px; background:var(--signal-tint);
  display:flex; align-items:center; justify-content:center; margin-bottom:16px;
}
.research-card .icon img{ width:26px; height:26px; }
.research-card h3{ font-size:17px; margin-bottom:8px; }
.research-card p{ color:var(--text-soft); font-size:14px; margin-bottom:0; }
.research-card .tags{ margin-top:14px; display:flex; flex-wrap:wrap; gap:6px; }
.research-card .tags span{
  font-family:var(--font-mono); font-size:11px; color:var(--signal-dark);
  background:var(--signal-tint); padding:3px 8px; border-radius:20px;
}
@media (max-width:900px){ .research-grid{ grid-template-columns:1fr 1fr; } }
@media (max-width:600px){ .research-grid{ grid-template-columns:1fr; } }

/* ---------- Quick links row ---------- */
.quicklinks{ display:grid; grid-template-columns:repeat(3,1fr); gap:18px; }
.quicklink{
  display:flex; align-items:center; justify-content:space-between;
  background:var(--ink); color:#fff; border-radius:var(--radius);
  padding:20px 22px; font-weight:700; font-size:15px;
  transition:background .15s;
}
.quicklink:hover{ background:var(--signal-dark); color:#fff; }
.quicklink .arrow{ font-size:18px; }
@media (max-width:900px){ .quicklinks{ grid-template-columns:1fr; } }

/* ---------- Footer ---------- */
footer.site-footer{
  background:var(--ink); color:#93A2B5; padding:40px 0 26px; margin-top:0;
}
footer.site-footer .wrap{ display:flex; justify-content:space-between; gap:24px; flex-wrap:wrap; }
footer.site-footer h4{ color:#fff; font-size:14px; margin-bottom:12px; }
footer.site-footer p, footer.site-footer li{ font-size:13px; color:#93A2B5; margin-bottom:6px; }
footer.site-footer a{ color:#93A2B5; }
footer.site-footer a:hover{ color:#fff; }
.footer-bottom{
  border-top:1px solid rgba(255,255,255,.1); margin-top:28px; padding-top:18px;
  text-align:center; font-size:12.5px; color:#6E7C8F;
}

/* ---------- Page header (interior pages) ---------- */
.page-hero{
  background:var(--ink); color:#fff; padding:52px 0 40px; position:relative; overflow:hidden;
}
.page-hero .wrap{ position:relative; }
.page-hero .eyebrow{ color:var(--signal); }
.page-hero .eyebrow::before{ background:var(--signal); }
.page-hero h2{ color:#fff; font-size:clamp(26px,3.6vw,38px); margin-bottom:8px; }
.page-hero p{ color:#B9C4D3; max-width:640px; font-size:15.5px; margin-bottom:0; }

/* ---------- Members ---------- */
.member-grid{ display:grid; grid-template-columns:repeat(3,1fr); gap:20px; }
.member-card{
  background:var(--paper-raise); border:1px solid var(--line); border-radius:var(--radius);
  padding:22px;
}
.member-card .avatar{
  width:46px; height:46px; border-radius:50%; background:var(--signal-tint); color:var(--signal-dark);
  display:flex; align-items:center; justify-content:center; font-family:var(--font-display); font-weight:700;
  margin-bottom:14px; font-size:16px;
}
.member-card h4{ font-size:15.5px; margin-bottom:2px; }
.member-card .tag{ font-family:var(--font-mono); font-size:11px; color:var(--text-mute); margin-bottom:10px; display:block; }
.member-card ul.interests li{ font-size:13.5px; color:var(--text-soft); padding:2px 0; }
.member-card .since{ font-family:var(--font-mono); font-size:11px; color:var(--signal-dark); margin-top:10px; display:inline-block; }
.member-card a.wp{ display:inline-block; margin-top:12px; font-weight:700; font-size:13px; }
@media (max-width:900px){ .member-grid{ grid-template-columns:1fr 1fr; } }
@media (max-width:600px){ .member-grid{ grid-template-columns:1fr; } }

.bsc-note{
  background:var(--signal-tint); border:1px dashed var(--signal); border-radius:var(--radius);
  padding:18px 22px; color:var(--signal-dark); font-size:14.5px; font-weight:600;
}

.alumni-toggle{
  display:inline-flex; align-items:center; gap:8px;
  background:none; border:1px solid var(--line); border-radius:8px;
  padding:10px 16px; font-family:var(--font-mono); font-size:13px;
  color:var(--ink); cursor:pointer; margin-bottom:18px;
}
.alumni-toggle:hover{ border-color:var(--signal); color:var(--signal-dark); }
.alumni-list{ display:none; }
.alumni-list.open{ display:block; }
.alumni-table{ width:100%; border-collapse:collapse; }
.alumni-table tr{ border-bottom:1px solid var(--line); }
.alumni-table td{ padding:12px 6px; font-size:14px; vertical-align:top; }
.alumni-table td.name{ font-weight:700; color:var(--ink); width:220px; }
.alumni-table td.detail{ color:var(--text-soft); }
.alumni-table td.detail .yrs{ font-family:var(--font-mono); font-size:12px; color:var(--signal-dark); }

.director-full{
  display:grid; grid-template-columns:180px 1fr; gap:32px; align-items:start;
  background:var(--paper-raise); border:1px solid var(--line); border-radius:14px; padding:30px;
}
.director-full img{ border-radius:12px; }
.director-full h3{ font-size:22px; margin-bottom:2px; }
.director-full .role{ color:var(--signal-dark); font-family:var(--font-mono); font-size:13px; margin-bottom:14px; }
.director-full p{ font-size:14.5px; color:var(--text-soft); margin-bottom:6px; }
@media (max-width:640px){ .director-full{ grid-template-columns:1fr; } }

/* ---------- Publications ---------- */
.pub-toolbar{
  display:flex; align-items:center; justify-content:space-between; flex-wrap:wrap; gap:16px;
  margin-bottom:30px; padding:20px 24px; background:var(--paper-raise); border:1px solid var(--line); border-radius:var(--radius);
}
.pub-toolbar .scholar{ display:flex; align-items:center; gap:12px; }
.pub-toolbar img{ width:32px; height:32px; }
.pub-list{ counter-reset:pub; }
.pub-item{
  display:flex; gap:16px; padding:16px 0; border-bottom:1px solid var(--line);
}
.pub-item::before{
  counter-increment:pub; content:counter(pub);
  font-family:var(--font-mono); color:var(--text-mute); font-size:13px; width:28px; flex-shrink:0; padding-top:2px;
}
.pub-item .body{ flex:1; font-size:14.5px; color:var(--text-soft); }
.pub-item .body strong{ color:var(--ink); }
.pub-item .links{ flex-shrink:0; display:flex; gap:8px; align-items:flex-start; padding-top:2px;}
.pub-item .links a{
  width:30px; height:30px; border-radius:7px; background:var(--signal-tint);
  display:flex; align-items:center; justify-content:center;
}
.pub-item .links img{ width:16px; height:16px; }
.pub-tabs{ display:flex; gap:10px; margin-bottom:22px; }
.pub-tab{
  font-family:var(--font-mono); font-size:13px; padding:9px 16px; border-radius:8px;
  border:1px solid var(--line); background:var(--paper-raise); cursor:pointer; color:var(--text-soft);
}
.pub-tab.active{ background:var(--ink); color:#fff; border-color:var(--ink); }
.pub-panel{ display:none; }
.pub-panel.active{ display:block; }

/* ---------- Seminars ---------- */
.seminar-item{
  background:var(--paper-raise); border:1px solid var(--line); border-left:3px solid var(--signal);
  border-radius:8px; padding:18px 20px; margin-bottom:14px;
}
.seminar-item p{ margin:0; font-size:14.5px; color:var(--text-soft); }
.seminar-item strong{ color:var(--ink); }

/* ---------- word cloud ---------- */
.topic-cloud{ display:flex; flex-wrap:wrap; gap:10px; }
.topic-cloud span{
  font-family:var(--font-mono); border:1px solid var(--line); border-radius:20px;
  padding:7px 14px; color:var(--text-soft); font-size:13px; background:var(--paper-raise);
}
.topic-cloud span.w1{ font-size:12px; }
.topic-cloud span.w2{ font-size:14px; }
.topic-cloud span.w3{ font-size:16px; color:var(--signal-dark); border-color:var(--signal); font-weight:700; }

/* utility */
.mt-40{ margin-top:40px; }
.text-center{ text-align:center; }