/* ============================================================
   CERL — Combustion Engineering Research Laboratory, IIT Delhi
   Single shared stylesheet. No build step, no framework.
   ============================================================ */

:root{
  --ink:#101418;
  --ink-soft:#20262e;
  --maroon:#7A1B2B;
  --maroon-dk:#5C1420;
  --ember:#E2703A;
  --paper:#FBFAF7;
  --paper-2:#F2EFE9;
  --slate:#5A6472;
  --line:#DBD6CC;
  --white:#fff;

  --serif:"Newsreader",Georgia,"Times New Roman",serif;
  --sans:"Public Sans","Helvetica Neue",Arial,sans-serif;

  --wrap:1120px;
  --gap:28px;
}

*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{animation:none!important;transition:none!important}
}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  font-size:17px;
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
}
img{max-width:100%;display:block}
a{color:var(--maroon);text-decoration:none;border-bottom:1px solid rgba(122,27,43,.28)}
a:hover{border-bottom-color:var(--maroon)}
:focus-visible{outline:2px solid var(--ember);outline-offset:3px}

h1,h2,h3,h4{font-family:var(--serif);font-weight:600;line-height:1.18;margin:0 0 .5em;letter-spacing:-.012em}
h1{font-size:clamp(2.1rem,4.6vw,3.3rem)}
h2{font-size:clamp(1.6rem,3vw,2.2rem)}
h3{font-size:1.22rem}
h4{font-size:1.02rem}
p{margin:0 0 1.05em;max-width:74ch}

.container{width:100%;max-width:var(--wrap);margin:0 auto;padding:0 22px}
.text-center{text-align:center}
.mt-lg{margin-top:34px}
.small{font-size:.92rem}
.muted{color:var(--slate)}

/* ---------- Header ---------- */
.site-header{background:var(--ink);color:var(--white);border-bottom:3px solid var(--maroon)}
.header-top{
  max-width:var(--wrap);margin:0 auto;padding:16px 22px;
  display:flex;align-items:center;gap:18px;flex-wrap:wrap;justify-content:space-between;
}
.brand{display:flex;align-items:center;gap:14px;border:0;color:inherit}
.brand:hover{border:0}
.brand-lockup{display:flex;align-items:center;gap:13px}
.iitd-logo{height:52px;width:auto}
.logo-slot{
  height:52px;width:52px;border:1px dashed rgba(255,255,255,.35);border-radius:50%;
  display:flex;align-items:center;justify-content:center;text-align:center;
  font-size:8px;line-height:1.15;color:rgba(255,255,255,.6);padding:4px;
}
.rule-v{width:1px;height:40px;background:rgba(255,255,255,.22)}
.brand-text{display:flex;flex-direction:column;line-height:1.25}
.brand-name{font-family:var(--serif);font-size:1.5rem;font-weight:600;letter-spacing:.02em}
.brand-sub{font-size:.72rem;color:rgba(255,255,255,.68);letter-spacing:.04em}
.header-affil{font-size:.8rem;color:rgba(255,255,255,.72);text-align:right;line-height:1.5}
.header-affil strong{color:#fff;font-weight:600}

.site-nav{background:var(--ink-soft)}
.site-nav ul{
  max-width:var(--wrap);margin:0 auto;padding:0 22px;
  list-style:none;display:flex;flex-wrap:wrap;gap:2px;
}
.site-nav a{
  display:block;padding:12px 16px;color:rgba(255,255,255,.82);
  font-size:.86rem;font-weight:500;border:0;border-bottom:3px solid transparent;
}
.site-nav a:hover{color:#fff;background:rgba(255,255,255,.06)}
.site-nav a.active{color:#fff;border-bottom-color:var(--ember)}
.nav-toggle{
  display:none;background:none;border:0;color:#fff;font-size:1.4rem;
  padding:10px 22px;cursor:pointer;
}

/* ---------- Hero ---------- */
.hero{
  background:var(--ink);color:#fff;padding:64px 0 72px;
  border-bottom:1px solid rgba(255,255,255,.08);
}
.hero-grid{display:grid;grid-template-columns:1.25fr .75fr;gap:48px;align-items:center}
.hero h1{color:#fff;margin-bottom:.35em}
.hero-affil{color:var(--ember);font-size:.95rem;font-weight:600;margin-bottom:1.1em}
.hero-statement{color:rgba(255,255,255,.82);font-size:1.05rem;max-width:56ch}
.hero-buttons{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}
.flame-art{width:100%;max-width:300px;margin:0 auto}

/* ---------- Buttons ---------- */
.btn{
  display:inline-block;padding:11px 20px;border-radius:2px;font-size:.88rem;
  font-weight:600;border:1px solid transparent;cursor:pointer;
}
.btn:hover{border-bottom-width:1px}
.btn-primary{background:var(--maroon);color:#fff;border-color:var(--maroon)}
.btn-primary:hover{background:var(--maroon-dk)}
.btn-outline{background:transparent;color:#fff;border-color:rgba(255,255,255,.45)}
.btn-outline:hover{border-color:#fff;background:rgba(255,255,255,.08)}
.btn-scholar{background:var(--ink);color:#fff;border-color:var(--ink)}
.btn-scholar:hover{background:var(--ink-soft)}
.btn-small{padding:8px 14px;font-size:.82rem}

/* ---------- Sections ---------- */
.section{padding:64px 0}
.section-alt{background:var(--paper-2);border-block:1px solid var(--line)}
.section-kicker{
  font-family:var(--serif);font-style:italic;color:var(--maroon);
  font-size:1rem;margin-bottom:4px;
}
.section-title{margin-bottom:.5em}
.section-intro{color:var(--slate);max-width:68ch}
.page-header{background:var(--paper-2);border-bottom:1px solid var(--line);padding:44px 0 38px}
.page-header h1{margin-bottom:.15em}
.page-header p{color:var(--slate);margin:0}

/* ---------- Grid / cards ---------- */
.grid{display:grid;gap:var(--gap)}
.grid-2{grid-template-columns:repeat(2,1fr)}
.grid-3{grid-template-columns:repeat(3,1fr)}
.card{background:var(--white);border:1px solid var(--line);display:flex;flex-direction:column}
.card-media{
  aspect-ratio:16/10;background:var(--paper-2);border-bottom:1px solid var(--line);
  display:flex;align-items:center;justify-content:center;color:var(--slate);
  font-size:.8rem;text-align:center;padding:14px;
}
.card-media img{width:100%;height:100%;object-fit:cover}
.card-body{padding:20px 22px 24px}
.card-body h3{margin-bottom:.4em}
.card-body p{font-size:.94rem;color:var(--slate);margin-bottom:0}
.tag{
  display:inline-block;font-size:.72rem;font-weight:600;color:var(--maroon);
  border:1px solid rgba(122,27,43,.3);padding:2px 8px;border-radius:2px;margin-bottom:10px;
}

/* ---------- Numbered research themes ---------- */
.theme{
  display:grid;grid-template-columns:60px 1fr;gap:24px;
  padding:30px 0;border-top:1px solid var(--line);
}
.theme:last-of-type{border-bottom:1px solid var(--line)}
.theme-num{
  font-family:var(--serif);font-size:1.7rem;color:var(--maroon);
  line-height:1;padding-top:4px;
}
.theme h3{margin-bottom:.35em}
.theme p{color:var(--slate);font-size:.97rem}
.theme-figure{
  margin-top:14px;border:1px solid var(--line);background:var(--paper-2);
  aspect-ratio:16/7;display:flex;align-items:center;justify-content:center;
  color:var(--slate);font-size:.8rem;text-align:center;padding:12px;
}
.theme-figure img{width:100%;height:100%;object-fit:cover}

/* ---------- People ---------- */
.team-group-title{
  margin:52px 0 20px;padding-bottom:8px;border-bottom:2px solid var(--maroon);
  font-size:1.35rem;
}
.pi-card{
  display:grid;grid-template-columns:250px 1fr;gap:36px;
  background:var(--white);border:1px solid var(--line);padding:30px;
}
.photo-placeholder{
  width:100%;aspect-ratio:3/4;background:var(--paper-2);border:1px solid var(--line);
  display:flex;align-items:center;justify-content:center;text-align:center;
  color:var(--slate);font-size:.78rem;padding:12px;object-fit:cover;
}
.pi-name{margin-bottom:.1em}
.pi-role{color:var(--maroon);font-weight:600;font-size:.95rem}
.pi-affil{color:var(--slate);font-size:.92rem;margin-bottom:18px}
.field-label{
  font-family:var(--serif);font-style:italic;color:var(--ink);
  font-size:1.02rem;margin-top:18px;margin-bottom:3px;
}
.pi-meta{display:flex;gap:10px;flex-wrap:wrap;margin-top:22px}
.pi-facts{list-style:none;padding:0;margin:0 0 4px}
.pi-facts li{
  padding:7px 0;border-bottom:1px dotted var(--line);font-size:.93rem;
  display:grid;grid-template-columns:110px 1fr;gap:14px;
}
.pi-facts li span{color:var(--slate)}

.people-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:22px}
.person-card{background:var(--white);border:1px solid var(--line)}
.person-photo{
  aspect-ratio:1/1;background:var(--paper-2);border-bottom:1px solid var(--line);
  display:flex;align-items:center;justify-content:center;color:var(--slate);font-size:.78rem;
}
.person-photo img{width:100%;height:100%;object-fit:cover}
.person-body{padding:15px 17px 19px}
.person-body h4{margin-bottom:.15em}
.person-role{color:var(--maroon);font-size:.8rem;font-weight:600;margin-bottom:7px}
.person-note{font-size:.86rem;color:var(--slate);margin:0}

.empty-slot{
  border:1px dashed var(--line);background:var(--white);padding:24px;
  color:var(--slate);font-size:.9rem;
}

/* ---------- Publications ---------- */
.pub-filter-note{
  background:var(--white);border-left:3px solid var(--maroon);
  padding:16px 20px;font-size:.92rem;color:var(--slate);margin-bottom:28px;
}
.pub-year-heading{
  font-size:1.15rem;margin:38px 0 4px;padding-bottom:6px;
  border-bottom:1px solid var(--line);color:var(--maroon);
}
.pub-item{
  display:grid;grid-template-columns:44px 1fr;gap:14px;
  padding:14px 0;border-bottom:1px solid var(--line);
}
.pub-num{color:var(--slate);font-size:.9rem;font-variant-numeric:tabular-nums;padding-top:2px}
.pub-item-title{font-family:var(--serif);font-size:1.03rem;line-height:1.35;margin-bottom:3px}
.pub-item-meta{font-size:.88rem;color:var(--slate)}
.pub-item-meta em{color:var(--maroon);font-style:normal;font-weight:600}
.pub-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:var(--line);border:1px solid var(--line);margin-bottom:30px}
.pub-stat{background:var(--white);padding:18px 20px}
.pub-stat b{display:block;font-family:var(--serif);font-size:1.7rem;color:var(--maroon);line-height:1.1}
.pub-stat span{font-size:.83rem;color:var(--slate)}

/* ---------- Facilities ---------- */
.facility-item{
  display:grid;grid-template-columns:300px 1fr;gap:30px;align-items:start;
  padding:28px 0;border-top:1px solid var(--line);
}
.facility-item:last-of-type{border-bottom:1px solid var(--line)}
.facility-item h3{margin-bottom:.3em}
.facility-item p{font-size:.95rem;color:var(--slate)}
.spec-list{list-style:none;padding:0;margin:10px 0 0;font-size:.89rem}
.spec-list li{padding:5px 0;border-bottom:1px dotted var(--line);color:var(--slate)}

/* ---------- Contact ---------- */
.contact-grid{display:grid;grid-template-columns:1fr 1fr;gap:44px}
.contact-block{margin-bottom:28px}
.contact-block h3{margin-bottom:.3em}
.contact-block p{font-size:.95rem;margin-bottom:0}
.map-frame{width:100%;height:380px;border:1px solid var(--line)}

/* ---------- News ---------- */
.news-list{list-style:none;padding:0;margin:0}
.news-list li{
  display:grid;grid-template-columns:130px 1fr;gap:20px;
  padding:16px 0;border-bottom:1px solid var(--line);
}
.news-date{color:var(--maroon);font-size:.85rem;font-weight:600;padding-top:2px}
.news-list p{margin:0;font-size:.95rem}

/* ---------- Editor notes (visible reminders for site maintainer) ---------- */
.placeholder-note{
  font-size:.84rem;color:var(--slate);background:var(--paper-2);
  border:1px dashed var(--line);padding:10px 13px;
}
code{font-family:ui-monospace,Menlo,Consolas,monospace;font-size:.85em;background:var(--paper-2);padding:1px 5px}

/* ---------- Footer ---------- */
.site-footer{background:var(--ink);color:rgba(255,255,255,.72);padding:48px 0 22px;font-size:.9rem}
.footer-grid{display:grid;grid-template-columns:1.6fr 1fr 1fr;gap:36px}
.site-footer h4{color:#fff;font-size:1rem;margin-bottom:.6em}
.site-footer p{margin:0;line-height:1.7}
.site-footer ul{list-style:none;padding:0;margin:0}
.site-footer li{padding:3px 0}
.site-footer a{color:rgba(255,255,255,.82);border-bottom-color:rgba(255,255,255,.2)}
.site-footer a:hover{color:#fff;border-bottom-color:#fff}
.footer-bottom{
  margin-top:34px;padding-top:18px;border-top:1px solid rgba(255,255,255,.12);
  font-size:.82rem;color:rgba(255,255,255,.5);
}

/* ---------- Responsive ---------- */
@media (max-width:960px){
  .hero-grid{grid-template-columns:1fr}
  .flame-art{display:none}
  .grid-3{grid-template-columns:repeat(2,1fr)}
  .people-grid{grid-template-columns:repeat(2,1fr)}
  .pi-card{grid-template-columns:190px 1fr;gap:24px}
  .contact-grid,.footer-grid{grid-template-columns:1fr}
  .facility-item{grid-template-columns:220px 1fr}
}
@media (max-width:680px){
  body{font-size:16px}
  .header-affil{display:none}
  .nav-toggle{display:block}
  .site-nav ul{display:none;flex-direction:column;padding-bottom:8px}
  .site-nav ul.open{display:flex}
  .grid-3,.grid-2,.people-grid,.pub-stats{grid-template-columns:1fr}
  .pi-card{grid-template-columns:1fr}
  .photo-placeholder{max-width:220px}
  .facility-item{grid-template-columns:1fr}
  .theme{grid-template-columns:1fr;gap:6px}
  .news-list li,.pi-facts li{grid-template-columns:1fr;gap:2px}
  .section{padding:44px 0}
}

/* ---------- Additions: real logos, hero figure, publications ---------- */
.iitd-logo{height:54px;width:auto;filter:brightness(0) invert(1)}
.cerl-logo{filter:none}
.logo-slot{display:none}

.hero-figure{border:1px solid rgba(255,255,255,.14);background:#fff;padding:14px}
.hero-figure img{width:100%}
.figcap{font-size:.78rem;color:var(--slate);margin:10px 0 0;line-height:1.5}
.hero .figcap{color:rgba(255,255,255,.55)}

.pub-jump{display:flex;gap:18px;flex-wrap:wrap;margin:0 0 6px;font-size:.9rem}
.pub-section-heading{
  margin:52px 0 6px;padding-bottom:10px;border-bottom:2px solid var(--maroon);
  font-size:1.5rem;
}
.pub-section-heading:first-of-type{margin-top:34px}
.cite-count{color:var(--maroon);font-weight:600}
.pub-item-meta+.pub-item-meta{margin-top:1px}

.theme-figure{aspect-ratio:auto;display:block;padding:14px;background:#fff}
.theme-figure img{width:100%;height:auto;object-fit:contain}
.theme-figure.tall img{max-height:420px;width:auto;margin:0 auto}

.pi-photo{width:100%;border:1px solid var(--line)}

/* Single-column variants used while photographs are not yet available */
.facility-item--nophoto{grid-template-columns:1fr}
.people-grid .person-card .person-body{padding:16px 18px 20px}
.pi-card .pi-photo{max-width:250px}

/* ---------- Hero slideshow (three photos, CSS-only crossfade) ---------- */
.hero-slideshow{position:relative;aspect-ratio:4/3;overflow:hidden}
.hero-slideshow img{
  position:absolute;inset:0;width:100%;height:100%;object-fit:cover;
  opacity:0;animation:heroFade 15s infinite;
}
.hero-slideshow img:nth-child(1){animation-delay:0s}
.hero-slideshow img:nth-child(2){animation-delay:5s}
.hero-slideshow img:nth-child(3){animation-delay:10s}
@keyframes heroFade{
  0%{opacity:0} 4%{opacity:1} 30%{opacity:1} 36%{opacity:0} 100%{opacity:0}
}
@media (prefers-reduced-motion:reduce){
  .hero-slideshow img{animation:none;opacity:0}
  .hero-slideshow img:first-child{opacity:1}
}

/* Card media now hosts real photos */
.card-media{padding:0;overflow:hidden}
.card-media img{width:100%;height:100%;object-fit:cover}

/* Person photo now hosts the SVG avatar or a real photo, cover-fit */
.person-photo img{width:100%;height:100%;object-fit:cover}
.person-photo{background:#F2EFE9}

/* Facility items always have an image now */
.facility-item .card-media img{object-fit:cover}