/* =========================================================
   AI for Digital Pathology — course site
   Palette grounded in H&E histology staining:
   hematoxylin violet + eosin rose on clinical white.
   ========================================================= */

:root{
  /* surfaces */
  --bg:        #ffffff;
  --bg-soft:   #f7f5fb;   /* faint hematoxylin tint */
  --bg-dark:   #1a1230;   /* deep slide-violet for the CTA/footer */

  /* ink */
  --ink:       #191325;
  --ink-soft:  #5c5570;
  --ink-faint: #8a8399;

  /* stain accents */
  --hema:       #5b2e91;  /* hematoxylin — nuclei violet */
  --hema-bright:#7c47cf;
  --eosin:      #e0447b;  /* eosin — rose pink */
  --eosin-soft: #f4a6c4;
  --teal:       #12a4b8;  /* the "digital scanner" accent, used sparingly */

  /* lines & fills */
  --line:      #ece7f4;
  --line-2:    #e0d8ee;
  --card:      #ffffff;

  --grad: linear-gradient(100deg, var(--hema) 0%, var(--eosin) 100%);

  /* type */
  --display: "Space Grotesk", system-ui, sans-serif;
  --body:    "Inter", system-ui, sans-serif;
  --mono:    "IBM Plex Mono", ui-monospace, monospace;

  --wrap: 1180px;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 1px 2px rgba(25,19,37,.04), 0 12px 30px -12px rgba(91,46,145,.18);
  --shadow-lift: 0 2px 4px rgba(25,19,37,.05), 0 26px 50px -18px rgba(91,46,145,.32);
}

/* ---------- reset ---------- */
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:var(--body);
  color:var(--ink);
  background:var(--bg);
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
img,svg{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
em{font-style:italic;color:var(--hema)}

.wrap{max-width:var(--wrap);margin:0 auto;padding:0 28px}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);border:0}

/* keyboard focus */
a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{
  outline:2.5px solid var(--hema-bright);
  outline-offset:3px;
  border-radius:6px;
}

/* ---------- type scale ---------- */
h1,h2,h3{font-family:var(--display);font-weight:600;line-height:1.08;letter-spacing:-.02em;color:var(--ink)}
h2{font-size:clamp(1.75rem,3.4vw,2.6rem);letter-spacing:-.025em}
h3{font-size:1.22rem;letter-spacing:-.01em}

.kicker{
  font-family:var(--mono);font-size:.75rem;font-weight:500;
  letter-spacing:.16em;text-transform:uppercase;color:var(--hema);
  margin-bottom:.9rem;
}
.kicker.on-dark{color:var(--eosin-soft)}
.eyebrow{
  font-family:var(--mono);font-size:.78rem;letter-spacing:.14em;
  text-transform:uppercase;color:var(--hema);margin-bottom:1.1rem;font-weight:500;
}
.grad{
  background:var(--grad);-webkit-background-clip:text;background-clip:text;
  color:transparent;
}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:.5rem;
  font-family:var(--display);font-weight:500;font-size:.98rem;
  padding:.82rem 1.5rem;border-radius:100px;border:1.5px solid transparent;
  cursor:pointer;transition:transform .18s ease, box-shadow .18s ease, background .18s ease, color .18s ease;
  white-space:nowrap;
}
.btn-sm{padding:.55rem 1.1rem;font-size:.9rem}
.btn-primary{background:var(--grad);color:#fff;box-shadow:0 10px 24px -10px rgba(224,68,123,.6)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 16px 30px -10px rgba(224,68,123,.7)}
.btn-ghost{background:transparent;color:var(--ink);border-color:var(--line-2)}
.btn-ghost:hover{border-color:var(--hema);color:var(--hema);transform:translateY(-2px)}
.btn-light{background:#fff;color:var(--hema);font-weight:600}
.btn-light:hover{transform:translateY(-2px);box-shadow:0 14px 30px -12px rgba(0,0,0,.4)}

/* =========================================================
   HEADER
   ========================================================= */
.site-header{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.82);
  backdrop-filter:saturate(160%) blur(12px);
  border-bottom:1px solid var(--line);
}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:70px}
.brand{display:flex;align-items:center;gap:.6rem;font-family:var(--display);font-weight:600;font-size:1.02rem;letter-spacing:-.01em}
.brand-mark{position:relative;width:26px;height:26px;flex:none}
.brand-mark .dot{position:absolute;border-radius:50%}
.dot-h{width:17px;height:17px;background:var(--hema);left:0;top:2px;mix-blend-mode:multiply}
.dot-e{width:15px;height:15px;background:var(--eosin);right:0;bottom:1px;mix-blend-mode:multiply;opacity:.9}

.main-nav{display:flex;align-items:center;gap:1.7rem}
.main-nav a{font-size:.94rem;color:var(--ink-soft);font-weight:500;transition:color .15s}
.main-nav a:hover{color:var(--ink)}
.main-nav .nav-cta{color:#fff}
.main-nav .nav-cta:hover{color:#fff}

.nav-toggle{display:none;flex-direction:column;gap:5px;background:none;border:0;padding:8px;cursor:pointer}
.nav-toggle span{width:24px;height:2px;background:var(--ink);border-radius:2px;transition:.25s}
.nav-toggle[aria-expanded="true"] span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] span:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}

/* =========================================================
   HERO
   ========================================================= */
.hero{position:relative;overflow:hidden;background:
   radial-gradient(1100px 460px at 82% -8%, rgba(224,68,123,.10), transparent 60%),
   radial-gradient(900px 420px at 8% 0%, rgba(91,46,145,.10), transparent 55%);
}
.hero-grid{
  display:grid;grid-template-columns:1.05fr .95fr;gap:56px;align-items:center;
  padding:76px 0 64px;
}
.hero-title{font-size:clamp(2.4rem,5.3vw,4rem);letter-spacing:-.035em;margin-bottom:1.4rem}
.hero-sub{font-size:1.12rem;color:var(--ink-soft);max-width:33rem;margin-bottom:2rem}
.hero-actions{display:flex;gap:.85rem;flex-wrap:wrap;margin-bottom:2.6rem}

.hero-stats{list-style:none;display:flex;gap:2.4rem;flex-wrap:wrap}
.hero-stats li{display:flex;flex-direction:column;gap:.15rem}
.hero-stats strong{font-family:var(--display);font-size:1.7rem;font-weight:600;color:var(--hema);letter-spacing:-.02em;line-height:1}
.hero-stats span{font-size:.82rem;color:var(--ink-faint)}

/* --- signature visual --- */
.hero-visual{position:relative}
.slide-card{
  background:#fff;border:1px solid var(--line-2);border-radius:var(--radius);
  box-shadow:var(--shadow-lift);overflow:hidden;
}
.slide-chrome{
  display:flex;align-items:center;justify-content:space-between;
  padding:11px 15px;border-bottom:1px solid var(--line);background:#fcfbfe;
}
.slide-label{font-family:var(--mono);font-size:.72rem;color:var(--ink-faint);letter-spacing:.02em}
.slide-live{font-family:var(--mono);font-size:.7rem;color:var(--eosin);display:flex;align-items:center;gap:.4rem;font-weight:500}
.slide-live i{width:7px;height:7px;border-radius:50%;background:var(--eosin);animation:pulse 1.6s infinite}
@keyframes pulse{0%,100%{opacity:1;transform:scale(1)}50%{opacity:.35;transform:scale(.8)}}
.wsi{width:100%;height:auto;display:block}

.hero-video {
  display: block;
  width: 100%;
  aspect-ratio: 520 / 400;
  object-fit: cover;
}

.float-chip{
  position:absolute;background:#fff;border:1px solid var(--line-2);
  border-radius:100px;padding:.4rem .8rem;display:flex;align-items:center;gap:.5rem;
  box-shadow:var(--shadow);font-family:var(--mono);font-size:.74rem;
}
.float-chip .k{color:var(--ink-faint)}
.float-chip .v{color:var(--hema);font-weight:600}
.chip-1{top:16%;left:-22px;animation:float 5s ease-in-out infinite}
.chip-2{bottom:14%;right:-18px;animation:float 6s ease-in-out infinite .6s}
.chip-2 .v{color:var(--eosin)}
@keyframes float{0%,100%{transform:translateY(0)}50%{transform:translateY(-9px)}}

/* --- marquee --- */
.marquee{border-top:1px solid var(--line);border-bottom:1px solid var(--line);overflow:hidden;background:#fff}
.marquee-track{display:flex;gap:0;width:max-content;animation:scroll 34s linear infinite}
.marquee-track span{
  font-family:var(--mono);font-size:.78rem;letter-spacing:.02em;color:var(--ink-faint);
  padding:14px 26px;position:relative;white-space:nowrap;
}
.marquee-track span::after{content:"·";position:absolute;right:-3px;color:var(--eosin-soft)}
@keyframes scroll{from{transform:translateX(0)}to{transform:translateX(-50%)}}

/* =========================================================
   SECTIONS
   ========================================================= */
.section{padding:92px 0}
.section-soft{background:var(--bg-soft);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.section-head{max-width:44rem;margin-bottom:52px}
.section-head h2{margin-bottom:1rem}
.lede{font-size:1.08rem;color:var(--ink-soft)}

/* ---------- audience split ---------- */
.split{display:grid;grid-template-columns:1fr 1fr;gap:26px}
.aud-card{
  background:var(--card);border:1px solid var(--line-2);border-radius:var(--radius);
  padding:34px 32px;box-shadow:var(--shadow);position:relative;overflow:hidden;
}
.aud-card::before{content:"";position:absolute;inset:0 auto 0 0;width:5px}
.aud-card:nth-child(1)::before{background:var(--hema)}
.aud-card:nth-child(2)::before{background:var(--eosin)}
.aud-tag{
  display:inline-block;font-family:var(--mono);font-size:.72rem;font-weight:500;
  letter-spacing:.08em;text-transform:uppercase;padding:.32rem .7rem;border-radius:100px;margin-bottom:1.2rem;
}
.tag-h{background:rgba(91,46,145,.1);color:var(--hema)}
.tag-e{background:rgba(224,68,123,.1);color:var(--eosin)}
.aud-card h3{margin-bottom:.7rem;font-size:1.35rem}
.aud-card > p{color:var(--ink-soft);margin-bottom:1.4rem}

.ticks{list-style:none;display:flex;flex-direction:column;gap:.7rem}
.ticks li{position:relative;padding-left:1.9rem;font-size:.97rem;color:var(--ink)}
.ticks li::before{
  content:"";position:absolute;left:0;top:.15em;width:1.15rem;height:1.15rem;border-radius:50%;
  background:var(--grad);
  -webkit-mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath fill='white' d='M9 16.2l-3.5-3.5L4 14.2 9 19.2 20 8.2l-1.5-1.5z'/%3E%3C/svg%3E") center/contain no-repeat;
  mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath fill='white' d='M9 16.2l-3.5-3.5L4 14.2 9 19.2 20 8.2l-1.5-1.5z'/%3E%3C/svg%3E") center/contain no-repeat;
}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:.7rem 1.6rem;margin-bottom:1.8rem}

/* ---------- outcomes ---------- */
.outcomes-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.outcome{
  background:var(--card);border:1px solid var(--line-2);border-radius:var(--radius);
  padding:30px 28px;transition:transform .2s ease, box-shadow .2s ease, border-color .2s;
}
.outcome:hover{transform:translateY(-4px);box-shadow:var(--shadow-lift);border-color:var(--eosin-soft)}
.outcome .num{font-family:var(--mono);font-size:.8rem;color:var(--eosin);font-weight:600;letter-spacing:.05em}
.outcome h3{margin:.55rem 0 .55rem;font-size:1.18rem}
.outcome p{font-size:.95rem;color:var(--ink-soft)}

/* ---------- curriculum ---------- */
.track-label{
  display:flex;align-items:center;gap:.7rem;font-family:var(--display);font-weight:600;
  font-size:1.02rem;color:var(--ink);margin:34px 0 14px;letter-spacing:-.01em;
}
.track-label:first-of-type{margin-top:0}
.track-dot{width:11px;height:11px;border-radius:50%;background:var(--ink-faint);flex:none}
.dot-tech{background:var(--hema)}
.dot-clin{background:var(--eosin)}

.chapters{display:flex;flex-direction:column;gap:10px;margin-bottom:8px}
.ch, .q{
  background:var(--card);border:1px solid var(--line-2);border-radius:var(--radius-sm);
  overflow:hidden;transition:border-color .2s, box-shadow .2s;
}
.ch[open], .q[open]{border-color:var(--hema-bright);box-shadow:var(--shadow)}
.ch summary, .q summary{
  display:flex;align-items:center;gap:1rem;padding:18px 22px;cursor:pointer;
  list-style:none;font-family:var(--display);font-weight:500;
}
.ch summary::-webkit-details-marker,.q summary::-webkit-details-marker{display:none}
.ch-no{
  font-family:var(--mono);font-size:.85rem;font-weight:600;color:var(--hema);
  width:2.2rem;flex:none;
}
.ch-title{flex:1;font-size:1.04rem;letter-spacing:-.01em}
.ch-caret{width:11px;height:11px;border-right:2px solid var(--ink-faint);border-bottom:2px solid var(--ink-faint);transform:rotate(45deg);transition:transform .25s;flex:none;margin-top:-4px}
.ch[open] .ch-caret,.q[open] .ch-caret{transform:rotate(-135deg);margin-top:2px;border-color:var(--hema)}
.ch-body,.q-body{padding:0 22px 22px 22px}
.ch-body{padding-left:4.4rem}
.ch-body > p,.q-body > p{color:var(--ink-soft);font-size:.97rem;margin-bottom:.9rem}
.q-body > p{margin-bottom:0}
.ch-topics{list-style:none;display:grid;grid-template-columns:1fr 1fr;gap:.45rem 1.4rem}
.ch-topics li{position:relative;padding-left:1.1rem;font-size:.9rem;color:var(--ink)}
.ch-topics li::before{content:"";position:absolute;left:0;top:.6em;width:5px;height:5px;border-radius:50%;background:var(--eosin)}

.q summary{gap:1rem}
.q summary{justify-content:space-between;font-size:1.04rem}

/* ---------- book ---------- */
.book-grid{display:grid;grid-template-columns:.82fr 1.18fr;gap:56px;align-items:center}
.book-visual{display:flex;justify-content:center}
.book-cover{
  width:290px;aspect-ratio:3/4;border-radius:14px;overflow:hidden;
  box-shadow:var(--shadow-lift);border:1px solid var(--line-2);
  display:flex;flex-direction:column;background:#fff;
  transform:rotate(-2.5deg);transition:transform .3s ease;
}
.book-cover:hover{transform:rotate(0) translateY(-4px)}
.cover-top{background:var(--bg-dark);padding:20px;height:56%;position:relative;overflow:hidden}
.cover-kicker{font-family:var(--mono);font-size:.66rem;letter-spacing:.14em;text-transform:uppercase;color:var(--eosin-soft);position:relative;z-index:2}
.cover-cells{position:absolute;inset:0}
.cover-body{padding:22px 20px;flex:1;display:flex;flex-direction:column;justify-content:center}
.cover-body h3{font-size:1.7rem;line-height:1.02;margin-bottom:.35rem}
.cover-sub{font-family:var(--display);color:var(--eosin);font-size:.92rem;margin-bottom:1.1rem}
.cover-auth{font-family:var(--mono);font-size:.72rem;color:var(--ink-faint);letter-spacing:.03em}
.book-copy h2{margin-bottom:1rem}
.book-copy > p{color:var(--ink-soft);font-size:1.05rem;margin-bottom:1.5rem}

/* ---------- authors ---------- */
.authors-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.author{
  background:var(--card);border:1px solid var(--line-2);border-radius:var(--radius);
  padding:32px 28px;text-align:center;box-shadow:var(--shadow);
}
.avatar{
  width:78px;height:78px;border-radius:50%;margin:0 auto 1.2rem;
  display:flex;align-items:center;justify-content:center;
  font-family:var(--display);font-weight:600;font-size:1.5rem;color:#fff;letter-spacing:.02em;
}
.av-1{background:linear-gradient(135deg,var(--hema),var(--hema-bright))}
.av-2{background:linear-gradient(135deg,var(--eosin),var(--eosin-soft))}
.av-3{background:linear-gradient(135deg,var(--teal),var(--hema-bright))}
.author h3{margin-bottom:.2rem}
.author .role{font-family:var(--mono);font-size:.76rem;letter-spacing:.03em;color:var(--eosin);text-transform:uppercase;margin-bottom:.9rem}
.author .bio{font-size:.92rem;color:var(--ink-soft)}

/* ---------- faq ---------- */
.faq-wrap{max-width:820px}
.faq{display:flex;flex-direction:column;gap:10px}

/* =========================================================
   ENROLL / CTA
   ========================================================= */
.enroll{background:
   radial-gradient(700px 300px at 15% 10%, rgba(224,68,123,.4), transparent 60%),
   radial-gradient(700px 340px at 88% 90%, rgba(124,71,207,.45), transparent 60%),
   var(--bg-dark);
  color:#fff;padding:82px 0;
}
.enroll-inner{display:grid;grid-template-columns:1fr 1fr;gap:48px;align-items:center}
.enroll h2{color:#fff;margin-bottom:1rem}
.enroll-copy p{color:rgba(255,255,255,.8);font-size:1.05rem;max-width:30rem}
.enroll-form{width:100%}
.field-row{display:flex;gap:.6rem;background:rgba(255,255,255,.08);border:1px solid rgba(255,255,255,.2);padding:.5rem;border-radius:100px;backdrop-filter:blur(6px)}
.field-row input{
  flex:1;background:transparent;border:0;color:#fff;font-family:var(--body);font-size:1rem;padding:.6rem 1.1rem;
}
.field-row input::placeholder{color:rgba(255,255,255,.55)}
.field-row input:focus{outline:none}
.form-note{font-family:var(--mono);font-size:.76rem;color:rgba(255,255,255,.6);margin-top:.9rem;padding-left:1.1rem}
.form-note.ok{color:var(--eosin-soft)}
.form-note.err{color:#ffb4b4}

/* =========================================================
   FOOTER
   ========================================================= */
.site-footer{background:#120c22;color:rgba(255,255,255,.7);padding:56px 0 30px}
.footer-grid{display:flex;justify-content:space-between;gap:40px;flex-wrap:wrap;padding-bottom:36px;border-bottom:1px solid rgba(255,255,255,.1)}
.footer-brand{max-width:340px}
.footer-brand{display:flex;flex-wrap:wrap;align-items:center;gap:.6rem;font-family:var(--display);font-weight:600;color:#fff}
.footer-brand .dot-h{mix-blend-mode:normal}
.footer-brand .dot-e{mix-blend-mode:normal}
.footer-tag{flex-basis:100%;font-family:var(--body);font-weight:400;font-size:.9rem;color:rgba(255,255,255,.55);margin-top:.4rem}
.footer-nav{display:flex;flex-wrap:wrap;gap:.4rem 1.6rem;align-content:flex-start}
.footer-nav a{font-size:.92rem;color:rgba(255,255,255,.72);transition:color .15s}
.footer-nav a:hover{color:#fff}
.footer-base{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap;padding-top:22px;font-size:.82rem;color:rgba(255,255,255,.45)}
.footer-base em{color:rgba(255,255,255,.6)}
.footer-credit{font-family:var(--mono);letter-spacing:.03em}

/* =========================================================
   REVEAL ANIMATION
   ========================================================= */
.reveal{opacity:0;transform:translateY(22px);transition:opacity .7s cubic-bezier(.2,.7,.2,1), transform .7s cubic-bezier(.2,.7,.2,1)}
.reveal.in{opacity:1;transform:none}

/* =========================================================
   RESPONSIVE
   ========================================================= */
@media (max-width:960px){
  .hero-grid{grid-template-columns:1fr;gap:44px;padding:56px 0 48px}
  .hero-visual{max-width:520px}
  .book-grid,.enroll-inner{grid-template-columns:1fr;gap:36px}
  .outcomes-grid,.authors-grid{grid-template-columns:1fr 1fr}
  .split{grid-template-columns:1fr}
}
@media (max-width:720px){
  .main-nav{
    position:absolute;top:70px;left:0;right:0;background:#fff;border-bottom:1px solid var(--line);
    flex-direction:column;align-items:stretch;gap:0;padding:8px 20px 20px;
    box-shadow:var(--shadow);transform:translateY(-8px);opacity:0;pointer-events:none;transition:.22s;
  }
  .main-nav.open{transform:none;opacity:1;pointer-events:auto}
  .main-nav a{padding:13px 4px;border-bottom:1px solid var(--line)}
  .main-nav .nav-cta{margin-top:12px;border-bottom:0;justify-content:center}
  .nav-toggle{display:flex}
  .section{padding:66px 0}
  .outcomes-grid,.authors-grid{grid-template-columns:1fr}
  .ch-body{padding-left:22px}
  .ch-topics,.two-col{grid-template-columns:1fr}
  .hero-stats{gap:1.6rem}
  .chip-1{left:6px}.chip-2{right:6px}
  .footer-grid{flex-direction:column;gap:26px}
}
@media (max-width:400px){
  .wrap{padding:0 18px}
  .hero-actions .btn{width:100%}
}

/* reduced motion */
@media (prefers-reduced-motion:reduce){
  *{animation:none !important;scroll-behavior:auto !important}
  .reveal{opacity:1;transform:none;transition:none}
}