/* ============================================================================
   CAS-NLP SERIES — landing page styles
   Design system shared with the lecture pages (dark premium academic).
   ========================================================================== */

:root{
  --bg0:#05070d; --bg1:#0a0f1a;
  --panel:rgba(8,13,24,.6); --panel-2:rgba(10,15,26,.72);
  --line:#1d2736; --line-2:#2c3a52;
  --text:#e9eef7; --text-2:#a8b3c7; --text-3:#5f6b80;
  --teal:#5eead4; --sky:#7dd3fc; --indigo:#818cf8; --amber:#fbbf24; --rose:#fb7185; --green:#34d399;
  --font-display:'Space Grotesk',system-ui,sans-serif;
  --font-body:'Inter',system-ui,sans-serif;
  --font-mono:'JetBrains Mono',ui-monospace,monospace;
  --wrap:1240px;
  --grad:linear-gradient(120deg,var(--teal),var(--sky) 45%,var(--indigo));
}

*,*::before,*::after{box-sizing:border-box}
html{font-size:115%;-webkit-text-size-adjust:100%;overflow-x:clip;scroll-behavior:smooth}
html,body{margin:0;padding:0}
body{
  background:var(--bg0);color:var(--text);
  font-family:var(--font-body);font-size:1.05rem;line-height:1.65;
  overflow-x:clip;
}
body::after{
  content:'';position:fixed;inset:0;z-index:-1;pointer-events:none;
  background:
    radial-gradient(52rem 30rem at 12% -6%,rgba(94,234,212,.075),transparent 60%),
    radial-gradient(50rem 34rem at 96% 8%,rgba(129,140,248,.08),transparent 62%),
    radial-gradient(46rem 30rem at 50% 118%,rgba(125,211,252,.05),transparent 60%),
    repeating-linear-gradient(0deg,transparent 0 47px,rgba(148,163,184,.035) 47px 48px),
    repeating-linear-gradient(90deg,transparent 0 47px,rgba(148,163,184,.035) 47px 48px);
}
img{max-width:100%}
a{color:var(--teal)}
h1,h2,h3{font-family:var(--font-display);line-height:1.12;margin:0}
.mono{font-family:var(--font-mono);letter-spacing:.08em;font-size:.78rem;color:var(--text-2)}
.dim{color:var(--text-3)}
.micro{font-size:.85rem}
.wrap{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:clamp(1.2rem,4vw,2.4rem)}
.grad{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
[hidden]{display:none!important}

.skip-link{position:absolute;left:-999px;top:0;background:var(--teal);color:#04231f;padding:.6rem 1rem;border-radius:0 0 8px 0;z-index:300;font-weight:600}
.skip-link:focus{left:0}
:focus-visible{outline:2px solid var(--teal);outline-offset:2px;border-radius:4px}

/* ---------------- scroll reveal ---------------- */
.js .reveal{opacity:0;transform:translateY(18px);transition:opacity .7s ease,transform .7s ease}
.js .reveal.revealed{opacity:1;transform:none}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.001s!important;animation-iteration-count:1!important;transition-duration:.001s!important}
  .js .reveal{opacity:1;transform:none}
}
.static .reveal,.static *{animation:none!important;transition:none!important}
.static .js .reveal{opacity:1;transform:none}

/* ---------------- top bar ---------------- */
.topbar{
  display:flex;align-items:center;justify-content:space-between;gap:1rem;
  padding:.9rem clamp(1.2rem,4vw,2.4rem);
  border-bottom:1px solid var(--line);
  background:rgba(5,8,14,.75);backdrop-filter:blur(12px);
  position:sticky;top:0;z-index:100;
}
.brand{display:flex;align-items:center;gap:.7rem;color:var(--text);text-decoration:none}
.brand img{width:2.5rem;height:2.5rem;object-fit:contain;border-radius:9px;background:rgba(8,13,24,.5)}
.brand-txt{display:flex;flex-direction:column;line-height:1.2}
.brand-txt strong{font-family:var(--font-display);font-size:1.05rem;letter-spacing:.05em}
.brand-txt small{font-family:var(--font-mono);font-size:.62rem;letter-spacing:.22em;color:var(--teal)}
.topbar-track{margin:0;font-size:.68rem;letter-spacing:.2em}
@media (max-width:760px){.topbar-track{display:none}}

/* ---------------- buttons ---------------- */
.btn{
  display:inline-flex;align-items:center;gap:.55rem;
  font-family:var(--font-mono);font-size:.8rem;letter-spacing:.1em;text-transform:uppercase;
  color:var(--text);text-decoration:none;
  border:1px solid var(--line-2);border-radius:10px;padding:.7rem 1.25rem;
  background:rgba(10,15,26,.6);transition:border-color .2s,background .2s,transform .2s,box-shadow .2s;
}
.btn:hover{border-color:var(--teal);background:rgba(94,234,212,.06);transform:translateY(-2px)}
.btn-accent{
  background:linear-gradient(120deg,var(--teal),var(--sky));color:#04231f;font-weight:700;border:none;
  box-shadow:0 6px 26px rgba(94,234,212,.25);
}
.btn-accent:hover{background:linear-gradient(120deg,#6ff2dd,#8fdaff);box-shadow:0 10px 34px rgba(94,234,212,.4);color:#04231f}
.btn-big{font-size:.88rem;padding:.85rem 1.7rem}

/* ---------------- hero ---------------- */
.hero{padding:clamp(4.5rem,12vh,8rem) 0 clamp(3rem,8vh,5rem)}
.kicker{
  display:flex;align-items:center;gap:.7rem;margin:0 0 1.5rem;
  font-family:var(--font-mono);font-size:.78rem;letter-spacing:.2em;color:var(--teal);
}
.kicker .knum{
  display:grid;place-items:center;min-width:2rem;height:1.9rem;padding-inline:.5rem;
  border:1px solid rgba(94,234,212,.35);border-radius:999px;color:var(--teal);font-size:.72rem;
}
.hero-title{
  font-size:clamp(2.6rem,6.6vw,5.2rem);font-weight:700;letter-spacing:-.02em;
  max-width:20ch;margin:0 0 1.4rem;
}
.hero-lede{font-size:clamp(1.12rem,2.1vw,1.38rem);color:var(--text-2);max-width:56ch;margin:0 0 1.6rem}
.hero-lede em{color:var(--text);font-style:italic}
.hero-meta{margin:0 0 2rem;font-size:.78rem;letter-spacing:.12em}
.hero-meta b{color:var(--teal);font-weight:700}
.hero-cta{display:flex;gap:.9rem;flex-wrap:wrap}

/* ---------------- featured card ---------------- */
.featured{padding:clamp(2rem,6vh,4rem) 0}
.feature-card{
  position:relative;display:grid;grid-template-columns:1.15fr .85fr;gap:clamp(1.5rem,3vw,3rem);
  border:1px solid var(--line-2);border-radius:22px;
  background:linear-gradient(160deg,rgba(10,15,26,.9),rgba(8,13,24,.72));
  padding:clamp(1.6rem,3.4vw,3rem);
  overflow:hidden;
  transition:border-color .25s,box-shadow .25s,transform .25s;
}
.feature-card::before{
  content:'';position:absolute;inset:0;pointer-events:none;opacity:0;transition:opacity .3s;
  background:radial-gradient(36rem 22rem at var(--mx,50%) var(--my,0%),rgba(94,234,212,.09),transparent 65%);
}
.feature-card::after{
  content:'';position:absolute;top:0;left:0;right:0;height:3px;
  background:var(--grad);opacity:.85;
}
.feature-card:hover{border-color:rgba(94,234,212,.45);box-shadow:0 24px 70px rgba(0,0,0,.5),0 0 0 1px rgba(94,234,212,.12);transform:translateY(-4px)}
.feature-card:hover::before{opacity:1}
.feature-main{min-width:0;display:flex;flex-direction:column;align-items:flex-start}
.feature-top{display:flex;align-items:center;gap:1rem;margin:0 0 1.1rem;flex-wrap:wrap}
.lecture-num{font-family:var(--font-mono);font-size:.8rem;letter-spacing:.22em;color:var(--sky)}
.badge-live{
  display:inline-flex;align-items:center;gap:.5rem;
  font-family:var(--font-mono);font-size:.68rem;letter-spacing:.18em;
  color:#052e2a;background:linear-gradient(120deg,var(--green),var(--teal));
  border-radius:999px;padding:.32rem .85rem;font-weight:700;
}
.badge-live i{width:.55rem;height:.55rem;border-radius:50%;background:#04443c;animation:pulse 1.8s infinite}
@keyframes pulse{0%,100%{opacity:1;transform:scale(1)}50%{opacity:.45;transform:scale(.78)}}
.feature-title{font-size:clamp(2rem,4vw,3.2rem);font-weight:700;margin:0 0 .7rem;letter-spacing:-.015em}
.feature-title a{color:var(--text);text-decoration:none;background-image:linear-gradient(120deg,var(--teal),var(--sky));background-size:0% 2px;background-repeat:no-repeat;background-position:0 100%;transition:background-size .3s,padding-bottom .3s;padding-bottom:2px}
.feature-title a:hover{background-size:100% 2px}
.feature-tag{margin:0 0 .7rem;font-family:var(--font-display);font-size:clamp(1.08rem,2vw,1.3rem);color:var(--sky)}
.feature-desc{margin:0 0 1.4rem;color:var(--text-2);max-width:58ch}
.topic-chips{display:flex;flex-wrap:wrap;gap:.5rem;margin:0 0 1.8rem;padding:0;list-style:none}
.topic-chips li{
  font-family:var(--font-mono);font-size:.72rem;letter-spacing:.06em;
  color:var(--text-2);border:1px solid var(--line-2);border-radius:999px;padding:.3rem .8rem;
  background:rgba(8,13,24,.5);
}
.feature-actions{margin-top:auto;display:flex;flex-direction:column;gap:.8rem}
.feature-hint{font-size:.64rem;letter-spacing:.16em;color:var(--text-3)}

/* featured card art */
.feature-art{display:grid;place-items:center;min-width:0}
.art-pipeline{
  display:flex;flex-direction:column;gap:0;width:min(100%,340px);
  border:1px solid var(--line);border-radius:16px;background:rgba(5,8,14,.55);
  padding:1.3rem;
}
.ap-stage{
  display:flex;flex-direction:column;gap:.3rem;
  border:1px solid var(--line);border-radius:10px;background:rgba(8,13,24,.6);
  padding:.6rem .8rem;
}
.ap-k{font-family:var(--font-mono);font-size:.6rem;letter-spacing:.2em;color:var(--text-3)}
.ap-v{font-family:var(--font-mono);font-size:.72rem;color:var(--text-2)}
.ap-v.out{color:#a7f3d0;border:1px solid rgba(52,211,153,.4);border-radius:7px;padding:.28rem .5rem;background:rgba(52,211,153,.08)}
.ap-chips{display:flex;gap:.3rem;flex-wrap:wrap}
.ap-chips b{font-family:var(--font-mono);font-weight:500;font-size:.68rem;color:var(--sky);border:1px solid rgba(125,211,252,.35);border-radius:6px;padding:.1rem .45rem;background:rgba(125,211,252,.06)}
.ap-bars{display:flex;gap:.3rem;align-items:flex-end;height:2.2rem}
.ap-bars i{width:.55rem;border-radius:3px 3px 0 0;background:linear-gradient(180deg,var(--indigo),rgba(129,140,248,.25));height:calc(var(--h) * 100%);animation:barbreathe 2.6s ease-in-out var(--i,0s) infinite}
.ap-bars i:nth-child(1){--i:0s}.ap-bars i:nth-child(2){--i:.2s}.ap-bars i:nth-child(3){--i:.4s}.ap-bars i:nth-child(4){--i:.6s}.ap-bars i:nth-child(5){--i:.8s}
@keyframes barbreathe{0%,100%{transform:scaleY(1)}50%{transform:scaleY(.72)}}
.ap-core{
  align-self:center;display:grid;place-items:center;width:3.6rem;height:3.6rem;border-radius:50%;
  border:1px solid rgba(94,234,212,.5);color:var(--teal);font-family:var(--font-mono);font-size:.72rem;letter-spacing:.12em;
  background:rgba(94,234,212,.06);position:relative;
}
.ap-core::after{content:'';position:absolute;inset:-7px;border-radius:50%;border:1px solid rgba(94,234,212,.25);animation:ring 2.4s ease-out infinite}
@keyframes ring{0%{transform:scale(.82);opacity:.9}100%{transform:scale(1.22);opacity:0}}
.ap-link{display:flex;justify-content:center;height:1.1rem;align-items:stretch}
.ap-link i{width:2px;background:linear-gradient(180deg,var(--line-2),rgba(94,234,212,.5));position:relative;overflow:hidden}
.ap-link i::after{content:'';position:absolute;left:0;top:-40%;width:100%;height:40%;background:var(--teal);animation:flow 1.6s linear infinite}
.ap-link:nth-child(7) i::after{animation-delay:.4s}
.ap-link:nth-child(9) i::after{animation-delay:.8s}
@keyframes flow{0%{top:-40%}100%{top:110%}}
@media (prefers-reduced-motion:reduce){
  .ap-link i::after,.ap-core::after,.ap-bars i,.badge-live i{animation:none}
}

/* feature stats strip */
.feature-stats{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:1rem;
  margin-top:1.2rem;
}
.fstat{
  border:1px solid var(--line);border-radius:12px;background:var(--panel);
  padding:.9rem 1.1rem;display:flex;flex-direction:column;gap:.15rem;
}
.fstat b{font-family:var(--font-display);font-size:1.5rem;color:var(--text)}
.fstat span{font-family:var(--font-mono);font-size:.6rem;letter-spacing:.2em;color:var(--text-3)}

/* ---------------- roadmap ---------------- */
.roadmap{padding:clamp(3.5rem,9vh,6rem) 0 clamp(2rem,5vh,3rem)}
.sec-head{max-width:64ch;margin-bottom:2.2rem}
.sec-head h2{font-size:clamp(1.9rem,4vw,3rem);margin:0 0 .8rem;letter-spacing:-.015em}
.sec-lede{color:var(--text-2);font-size:1.1rem;margin:0}
.lecture-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:1.2rem}
.lec-card{
  position:relative;display:flex;flex-direction:column;gap:.7rem;
  border:1px solid var(--line);border-radius:16px;background:var(--panel-2);
  padding:1.5rem 1.5rem 1.3rem;min-height:100%;
  transition:border-color .2s,transform .2s,box-shadow .2s;
}
a.lec-card{text-decoration:none;color:var(--text)}
a.lec-card:hover{border-color:rgba(94,234,212,.45);transform:translateY(-4px);box-shadow:0 18px 46px rgba(0,0,0,.45)}
.lec-card.soon{opacity:.78;border-style:dashed;background:rgba(8,13,24,.4)}
.lec-card.soon:hover{transform:none;box-shadow:none;border-color:var(--line-2)}
.lec-top{display:flex;align-items:center;justify-content:space-between;gap:.6rem}
.lec-num{font-family:var(--font-mono);font-size:.74rem;letter-spacing:.22em;color:var(--sky)}
.badge-soon{
  display:inline-flex;align-items:center;gap:.4rem;
  font-family:var(--font-mono);font-size:.6rem;letter-spacing:.16em;color:var(--amber);
  border:1px solid rgba(251,191,36,.4);border-radius:999px;padding:.24rem .7rem;
}
.lec-title{font-size:1.32rem;font-weight:600;letter-spacing:-.01em}
.lec-blurb{margin:0;color:var(--text-2);font-size:.95rem;flex:1}
.lec-topics{display:flex;flex-wrap:wrap;gap:.4rem;margin:.2rem 0 0;padding:0;list-style:none}
.lec-topics li{font-family:var(--font-mono);font-size:.62rem;letter-spacing:.05em;color:var(--text-3);border:1px solid var(--line);border-radius:999px;padding:.18rem .6rem}
.lec-go{
  display:inline-flex;align-items:center;gap:.5rem;margin-top:.9rem;
  font-family:var(--font-mono);font-size:.74rem;letter-spacing:.14em;color:var(--teal);
}
.lec-card.soon .lec-go{color:var(--text-3)}
.lec-lock{font-size:.8rem}

/* deep dive link inside lecture card */
.lec-dive{
  display:inline-flex;align-items:center;gap:.5rem;margin-top:.3rem;
  font-family:var(--font-mono);font-size:.72rem;letter-spacing:.1em;
  color:var(--amber);text-decoration:none;
  border:1px solid rgba(251,191,36,.35);border-radius:8px;padding:.35rem .7rem;
  background:rgba(251,191,36,.06);transition:border-color .2s,background .2s;
}
.lec-dive:hover{border-color:rgba(251,191,36,.6);background:rgba(251,191,36,.12);text-decoration:none}
.dive-ico{color:var(--amber);font-size:.85rem}

/* deep dive standalone card */
.dive-card{
  border:1px solid rgba(94,234,212,.45);
  background:linear-gradient(160deg,rgba(10,15,26,.92),rgba(94,234,212,.04));
  position:relative;
}
.dive-card::before{
  content:'';position:absolute;top:0;left:0;right:0;height:3px;
  background:linear-gradient(120deg,var(--teal),var(--sky));opacity:.85;
}
.dive-card:hover{border-color:rgba(94,234,212,.65);box-shadow:0 18px 46px rgba(0,0,0,.45),0 0 0 1px rgba(94,234,212,.12)}
.badge-dive{
  display:inline-flex;align-items:center;gap:.4rem;
  font-family:var(--font-mono);font-size:.6rem;letter-spacing:.16em;
  color:#04231f;background:linear-gradient(120deg,var(--teal),var(--sky));
  border-radius:999px;padding:.24rem .7rem;font-weight:700;
}
.ghost-card{
.lec-dive{
  display:inline-flex;align-items:center;gap:.5rem;margin-top:.3rem;
  font-family:var(--font-mono);font-size:.72rem;letter-spacing:.1em;
  color:var(--amber);text-decoration:none;
  border:1px solid rgba(251,191,36,.35);border-radius:8px;padding:.35rem .7rem;
  background:rgba(251,191,36,.06);transition:border-color .2s,background .2s;
}
.lec-dive:hover{border-color:rgba(251,191,36,.6);background:rgba(251,191,36,.12);text-decoration:none}
.dive-ico{color:var(--amber);font-size:.85rem}
.ghost-card{
  display:flex;flex-direction:column;align-items:center;justify-content:center;gap:.5rem;
  border:1.5px dashed var(--line-2);border-radius:16px;min-height:230px;
  color:var(--text-3);text-align:center;padding:1.5rem;
}
.ghost-card b{font-family:var(--font-mono);font-size:.78rem;letter-spacing:.2em;font-weight:500}
.ghost-card span{font-size:.88rem;max-width:30ch}

/* ---------------- why trio ---------------- */
.why{padding:clamp(2.5rem,7vh,4.5rem) 0 clamp(4rem,9vh,6rem)}
.trio{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:1.2rem}
.trio-card{
  border:1px solid var(--line);border-radius:16px;background:var(--panel);
  padding:1.7rem 1.6rem;
}
.trio-ico{display:grid;place-items:center;width:2.6rem;height:2.6rem;border-radius:10px;border:1px solid rgba(94,234,212,.35);color:var(--teal);font-size:1rem;margin-bottom:1rem;background:rgba(94,234,212,.05)}
.trio-card h3{font-size:1.25rem;margin:0 0 .55rem}
.trio-card p{margin:0;color:var(--text-2);font-size:.97rem}
.trio-card .mono{font-size:.72rem}

/* ---------------- footer ---------------- */
.footer{border-top:1px solid var(--line);padding:2.6rem 0 2rem;background:rgba(5,8,14,.6)}
.footer-grid{display:flex;justify-content:space-between;gap:1.6rem;flex-wrap:wrap}
.f-brand{display:flex;align-items:center;gap:.8rem;font-size:1.05rem;margin:0 0 .4rem}
.f-brand img{width:3rem;height:3rem;object-fit:contain;border-radius:9px;background:rgba(8,13,24,.5)}
.footer p{margin:.2rem 0}
.f-right{text-align:right}
.footer-note{margin-top:1.8rem}

/* ---------------- responsive ---------------- */
@media (max-width:900px){
  .feature-card{grid-template-columns:1fr}
  .feature-art{order:-1}
  .art-pipeline{display:none}
  .f-right{text-align:left}
}