/* ============================================================
   Dr. Riman Mandal — academic portfolio
   Palette encodes the research: cool teal = an active/running host,
   grey = idle. One accent, meant.
   ============================================================ */
:root{
  --bg:#F5F7F9;
  --surface:#FFFFFF;
  --surface-2:#EEF2F5;
  --ink:#101922;
  --muted:#5B6C7D;
  --faint:#8695A4;
  --rule:#D8E0E7;
  --active:#0E8C90;      /* running host */
  --active-ink:#0B6E71;
  --draw:#D98A1F;        /* energy draw / hot */
  --idle:#AEBBC8;

  --display:"Newsreader",Georgia,"Times New Roman",serif;
  --body:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --mono:"IBM Plex Mono",ui-monospace,"SF Mono",Menlo,monospace;

  --pad:clamp(1.15rem,5vw,4.5rem);
  --maxw:1080px;
}
[data-theme="dark"]{
  --bg:#0C141B;
  --surface:#111B24;
  --surface-2:#16222D;
  --ink:#E8EEF3;
  --muted:#9DAEBD;
  --faint:#6E8092;
  --rule:#22323F;
  --active:#22B3B7;
  --active-ink:#3ECBCF;
  --draw:#E9A94A;
  --idle:#3A4C5C;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;background:var(--bg);color:var(--ink);
  font-family:var(--body);font-size:1rem;line-height:1.6;
  -webkit-font-smoothing:antialiased;
  transition:background .3s,color .3s;
}
a{color:inherit}
img{max-width:100%;display:block}
h1,h2,h3{font-family:var(--display);font-weight:600;line-height:1.14;letter-spacing:-.01em;margin:0}
p{margin:0 0 1em}
.wrap{max-width:var(--maxw);margin:0 auto;padding-left:var(--pad);padding-right:var(--pad)}
.eyebrow{font-family:var(--mono);font-size:.72rem;letter-spacing:.14em;text-transform:uppercase;color:var(--active-ink);margin:0 0 .9rem}

/* ---------- nav ---------- */
nav{
  position:sticky;top:0;z-index:60;background:color-mix(in srgb,var(--bg) 88%,transparent);
  backdrop-filter:blur(10px);border-bottom:1px solid var(--rule);
}
.navrow{display:flex;align-items:center;gap:1.4rem;height:58px}
.navlinks{display:flex;gap:1.4rem;margin-left:auto;align-items:center;overflow-x:auto;scrollbar-width:none}
.navlinks::-webkit-scrollbar{display:none}
.navrow a{
  font-family:var(--mono);font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;
  color:var(--muted);text-decoration:none;white-space:nowrap;padding:.2rem 0;border-bottom:2px solid transparent;
}
.navrow a:hover,.navrow a:focus-visible,.navrow a[aria-current="page"]{color:var(--ink);border-bottom-color:var(--draw)}
.navrow .brand{color:var(--ink);font-weight:500;border:0;font-size:.8rem}
.themetoggle{
  background:transparent;border:1px solid var(--rule);border-radius:2px;color:var(--muted);
  font-family:var(--mono);font-size:.7rem;padding:.35rem .55rem;cursor:pointer;letter-spacing:.06em;flex:none;
}
.themetoggle:hover{border-color:var(--active);color:var(--active-ink)}

/* ---------- hero ---------- */
header.hero{padding:clamp(2.5rem,7vw,4.5rem) 0 clamp(1.5rem,4vw,2.5rem)}
.herotop{display:grid;grid-template-columns:1fr;gap:1.75rem;align-items:start}
@media(min-width:760px){.herotop{grid-template-columns:1fr auto;gap:2.5rem}}
h1.name{font-size:clamp(2.4rem,7vw,4rem)}
.tagline{font-family:var(--display);font-size:clamp(1.15rem,2.8vw,1.6rem);font-weight:400;color:var(--muted);margin-top:.6rem;max-width:20ch}
.lede{max-width:52ch;margin-top:1.3rem;font-size:1.06rem;color:var(--ink)}
.portrait{width:132px;height:132px;border-radius:3px;border:1px solid var(--rule);
  background:var(--surface-2);display:flex;align-items:center;justify-content:center;overflow:hidden}
.portrait img{width:100%;height:100%;object-fit:contain;object-position:center bottom}
.portrait span{font-family:var(--display);font-size:2.6rem;color:var(--faint)}
.navrow .brand{display:flex;align-items:center;gap:.5rem}
.navrow .brand img{width:22px;height:22px;object-fit:contain}
.actions{display:flex;flex-wrap:wrap;gap:.6rem;margin-top:1.6rem}
.btn{font-family:var(--mono);font-size:.76rem;letter-spacing:.04em;text-decoration:none;
  padding:.62rem 1.05rem;border:1px solid var(--ink);border-radius:2px;background:var(--ink);color:var(--bg)}
.btn.ghost{background:transparent;color:var(--ink)}
.btn:hover{background:var(--active);border-color:var(--active);color:#fff}

/* ---------- signature diagram ---------- */
.rack{margin-top:clamp(2rem,5vw,3rem);background:var(--surface);border:1px solid var(--rule);border-radius:3px;padding:1.15rem 1.15rem 1rem}
.rackhead{display:flex;flex-wrap:wrap;gap:.4rem 1.2rem;align-items:baseline;margin-bottom:1rem}
.rackhead .t{font-family:var(--mono);font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:var(--muted)}
.rackhead .v{font-family:var(--mono);font-size:.7rem;color:var(--ink);margin-left:auto}
.rackhead .v b{font-weight:600}
.rackhead .v .on{color:var(--active-ink)}
.rackhead .v .off{color:var(--faint)}
.stage{position:relative;display:grid;grid-template-columns:repeat(6,1fr);gap:.45rem}
.host{border:1px solid var(--rule);border-radius:2px;padding:.3rem;background:var(--surface-2);transition:opacity .5s,border-color .5s,background .5s}
.host.off{opacity:.5;background:transparent;border-style:dashed}
.slot{height:12px;margin-bottom:3px;border-radius:1px;background:color-mix(in srgb,var(--rule) 55%,transparent)}
.slot:last-child{margin-bottom:0}
.hlabel{font-family:var(--mono);font-size:.56rem;color:var(--faint);text-align:center;margin-top:.3rem;letter-spacing:.04em}
.vm{position:absolute;height:12px;border-radius:1px;background:var(--active);
  transition:transform .85s cubic-bezier(.65,0,.2,1),background .5s;will-change:transform}
.vm.hot{background:var(--draw)}
.caption{font-family:var(--mono);font-size:.68rem;color:var(--muted);margin-top:.85rem;line-height:1.5}

/* ---------- metrics ---------- */
.metrics{display:grid;grid-template-columns:repeat(2,1fr);gap:1px;background:var(--rule);border:1px solid var(--rule);border-radius:3px;overflow:hidden;margin-top:clamp(1.75rem,4vw,2.5rem)}
@media(min-width:640px){.metrics{grid-template-columns:repeat(4,1fr)}}
.metric{background:var(--surface);padding:1.15rem 1.1rem}
.metric b{display:block;font-family:var(--display);font-size:1.95rem;font-weight:600;letter-spacing:-.02em}
.metric span{font-family:var(--mono);font-size:.66rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}

/* ---------- sections ---------- */
section.band{padding:clamp(2.5rem,6vw,4rem) 0;border-top:1px solid var(--rule)}
.band h2{font-size:clamp(1.5rem,3.6vw,2rem);margin-bottom:.3rem}
.band .kicker{font-family:var(--mono);font-size:.7rem;letter-spacing:.12em;text-transform:uppercase;color:var(--active-ink);margin-bottom:.85rem}
.seelink{font-family:var(--mono);font-size:.72rem;color:var(--active-ink);text-decoration:none;border-bottom:1px solid transparent}
.seelink:hover{border-bottom-color:var(--active)}

/* research cards */
.research{display:grid;grid-template-columns:1fr;gap:1px;background:var(--rule);border:1px solid var(--rule);border-radius:3px;overflow:hidden;margin-top:1.4rem}
@media(min-width:720px){.research{grid-template-columns:1fr 1fr}}
.rcard{background:var(--surface);padding:1.25rem 1.2rem;display:block;text-decoration:none;transition:background .25s}
.rcard:hover{background:var(--surface-2)}
.rcard h3{font-size:1.08rem;display:flex;align-items:center;gap:.5rem}
.rcard h3::before{content:"";width:9px;height:9px;border-radius:50%;background:var(--active);flex:none}
.rcard.future h3::before{background:var(--idle)}
.rcard p{margin:.5rem 0 0;color:var(--muted);font-size:.94rem}

/* publication entries */
.entry{padding:1.05rem 0;border-top:1px solid var(--rule)}
.entry:first-child{border-top:0}
.entry .meta{font-family:var(--mono);font-size:.68rem;letter-spacing:.05em;color:var(--faint);text-transform:uppercase;margin-bottom:.3rem;display:flex;gap:.75rem;flex-wrap:wrap}
.entry .meta .flag{color:var(--draw)}
.entry .title{font-family:var(--display);font-weight:600;font-size:1.06rem;line-height:1.3}
.entry .authors{color:var(--muted);font-size:.92rem;margin-top:.3rem}
.entry .authors b{color:var(--ink);font-weight:600}
.entry .venue{color:var(--faint);font-size:.9rem;font-style:italic}
.entry .foot{display:flex;flex-wrap:wrap;gap:.5rem;align-items:center;margin-top:.55rem}
.tag{font-family:var(--mono);font-size:.62rem;letter-spacing:.05em;text-transform:uppercase;color:var(--muted);border:1px solid var(--rule);padding:.13rem .42rem;border-radius:2px}
.tag.if{color:var(--draw);border-color:color-mix(in srgb,var(--draw) 40%,var(--rule))}
.doi{font-family:var(--mono);font-size:.68rem;color:var(--active-ink);text-decoration:none;border-bottom:1px solid transparent}
.doi:hover{border-bottom-color:var(--active)}

/* filters */
.filters{display:flex;flex-wrap:wrap;gap:.4rem;margin:1.4rem 0 .5rem}
.filters button{font-family:var(--mono);font-size:.7rem;letter-spacing:.05em;text-transform:uppercase;
  background:var(--surface);border:1px solid var(--rule);color:var(--muted);padding:.35rem .7rem;border-radius:2px;cursor:pointer}
.filters button[aria-pressed="true"]{background:var(--ink);color:var(--bg);border-color:var(--ink)}
.grouphead{font-family:var(--mono);font-size:.72rem;letter-spacing:.1em;text-transform:uppercase;color:var(--active-ink);margin:2rem 0 .3rem}

/* teaching */
.role{padding:1.15rem 0;border-top:1px solid var(--rule)}
.role:first-of-type{border-top:0}
.role .meta{font-family:var(--mono);font-size:.68rem;letter-spacing:.05em;color:var(--faint);text-transform:uppercase;margin-bottom:.3rem}
.role h3{font-size:1.05rem;font-weight:600}
.role .where{color:var(--muted);font-size:.93rem;margin-top:.25rem}
.chips{display:flex;flex-wrap:wrap;gap:.35rem;margin-top:.6rem;padding:0;list-style:none}
.chips li{font-family:var(--mono);font-size:.68rem;color:var(--ink);background:var(--surface);border:1px solid var(--rule);padding:.2rem .5rem;border-radius:2px}

/* students corner */
.corner{display:grid;grid-template-columns:1fr;gap:1px;background:var(--rule);border:1px solid var(--rule);border-radius:3px;overflow:hidden;margin-top:1.3rem}
.ccourse{background:var(--surface);padding:1.1rem 1.15rem}
.ccourse .top{display:flex;align-items:center;gap:.6rem;flex-wrap:wrap}
.ccourse h3{font-size:1.02rem;font-weight:600}
.status{font-family:var(--mono);font-size:.6rem;letter-spacing:.08em;text-transform:uppercase;padding:.13rem .45rem;border-radius:2px;border:1px solid}
.status.live{color:var(--active-ink);border-color:color-mix(in srgb,var(--active) 45%,var(--rule))}
.status.soon{color:var(--faint);border-color:var(--rule)}
.matlist{display:flex;flex-wrap:wrap;gap:.4rem;margin-top:.7rem;padding:0;list-style:none}
.matlist li{font-family:var(--mono);font-size:.68rem;padding:.22rem .5rem;border-radius:2px;border:1px solid var(--rule);color:var(--muted)}
.matlist li.on{color:var(--active-ink);border-color:color-mix(in srgb,var(--active) 40%,var(--rule))}
.matlist a{text-decoration:none;color:inherit}

/* research impact by source */
.impact{display:grid;grid-template-columns:1fr;gap:1px;background:var(--rule);border:1px solid var(--rule);border-radius:3px;overflow:hidden;margin-top:1.3rem}
@media(min-width:640px){.impact{grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}}
.srccard{background:var(--surface);padding:1.1rem 1.15rem}
.srcname{font-family:var(--mono);font-size:.68rem;letter-spacing:.1em;text-transform:uppercase;color:var(--active-ink);margin-bottom:.7rem}
.srcstats{display:flex;flex-wrap:wrap;gap:1.2rem}
.srcstat b{display:block;font-family:var(--display);font-size:1.5rem;font-weight:600;letter-spacing:-.02em;line-height:1.1}
.srcstat span{font-family:var(--mono);font-size:.62rem;letter-spacing:.07em;text-transform:uppercase;color:var(--muted)}
.srcdate{font-family:var(--mono);font-size:.62rem;color:var(--faint);margin-top:.8rem;letter-spacing:.04em}

/* contact form */
.cform{margin-top:1.4rem;max-width:560px}
.cfrow{display:grid;grid-template-columns:1fr;gap:.8rem}
@media(min-width:560px){.cfrow{grid-template-columns:1fr 1fr}}
.cform label{display:block;font-family:var(--mono);font-size:.68rem;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin-bottom:.8rem}
.cform input,.cform textarea{display:block;width:100%;margin-top:.35rem;background:var(--surface);border:1px solid var(--rule);border-radius:2px;
  color:var(--ink);font-family:var(--body);font-size:.95rem;padding:.6rem .7rem;text-transform:none;letter-spacing:normal}
.cform input:focus,.cform textarea:focus{outline:2px solid var(--draw);outline-offset:1px;border-color:var(--active)}
.cform textarea{resize:vertical}
.cfoot{display:flex;align-items:center;gap:1rem;flex-wrap:wrap}
.cform button{font-family:var(--mono);font-size:.76rem;letter-spacing:.04em;padding:.62rem 1.1rem;border:1px solid var(--ink);border-radius:2px;background:var(--ink);color:var(--bg);cursor:pointer}
.cform button:hover{background:var(--active);border-color:var(--active);color:#fff}
.cform button:disabled{opacity:.5;cursor:default}
.cstatus{font-family:var(--mono);font-size:.72rem;color:var(--active-ink)}
.cstatus.err{color:var(--draw)}

/* contact */
.contactgrid{display:grid;grid-template-columns:1fr;gap:.6rem;margin-top:1.3rem}
@media(min-width:600px){.contactgrid{grid-template-columns:1fr 1fr}}
.contactgrid a{font-family:var(--mono);font-size:.82rem;text-decoration:none;padding:.75rem .9rem;background:var(--surface);border:1px solid var(--rule);border-radius:2px;display:flex;justify-content:space-between;gap:1rem;transition:border-color .2s}
.contactgrid a:hover{border-color:var(--active);color:var(--active-ink)}
.contactgrid a span{color:var(--faint)}

/* page intro (subpages) */
.pageintro{padding:clamp(2rem,6vw,3.5rem) 0 1.5rem}
.pageintro h1{font-size:clamp(2rem,5vw,3rem)}
.summary{font-family:var(--mono);font-size:.72rem;color:var(--muted);margin-top:.8rem;letter-spacing:.03em}

footer{border-top:1px solid var(--rule);padding:2rem 0 3rem;font-family:var(--mono);font-size:.68rem;color:var(--faint);letter-spacing:.03em;line-height:1.7}

:focus-visible{outline:2px solid var(--draw);outline-offset:3px}
@media(prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}html{scroll-behavior:auto}}