:root{
  --paper:#EAEDE6;
  --paper-2:#DFE4DA;
  --ink:#1B2420;
  --ink-soft:#4B5750;
  --patogen:#AC3B2E;
  --patogen-deep:#7C2A21;
  --healer:#1F7A6C;
  --healer-deep:#14554A;
  --gold:#C08A2C;
  --line: rgba(27,36,32,0.14);
}
*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:'Literata', serif;
  font-size:17px;
  line-height:1.7;
}
h1,h2,h3{
  font-family:'Fraunces', serif;
  font-weight:600;
  letter-spacing:-0.01em;
  margin:0;
}
.eyebrow{
  font-family:'IBM Plex Mono', monospace;
  font-size:0.72rem;
  letter-spacing:0.14em;
  text-transform:uppercase;
  color:var(--ink-soft);
}
.wrap{
  max-width:880px;
  margin:0 auto;
  padding:0 28px;
}

/* ---------- HERO ---------- */
.hero{
  position:relative;
  padding:96px 0 72px;
  overflow:hidden;
}
.hero .wrap{
  display:grid;
  grid-template-columns:1.3fr 0.9fr;
  gap:40px;
  align-items:center;
}
.hero .eyebrow{margin-bottom:18px;}
.hero h1{
  font-size:clamp(2.3rem, 5vw, 3.4rem);
  line-height:1.05;
}
.hero h1 .split{
  background:linear-gradient(92deg, var(--patogen) 0%, var(--patogen) 46%, var(--healer) 54%, var(--healer) 100%);
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
}
.hero p.lead{
  margin-top:20px;
  font-size:1.08rem;
  color:var(--ink-soft);
  max-width:52ch;
}
.capsid-hero{width:100%; height:auto;}

.tags{
  display:flex; flex-wrap:wrap; gap:8px; margin-top:26px;
}
.tag{
  font-family:'IBM Plex Mono', monospace;
  font-size:0.7rem;
  letter-spacing:0.04em;
  padding:5px 10px;
  border:1px solid var(--line);
  border-radius:100px;
  color:var(--ink-soft);
}

/* ---------- SPINE LAYOUT ---------- */
.spine-container{
  position:relative;
  max-width:880px;
  margin:0 auto;
  padding:0 28px 40px;
}
.spine{
  position:absolute;
  left:28px;
  top:0;
  bottom:0;
  width:2px;
  background:linear-gradient(180deg, var(--patogen) 0%, var(--patogen) 30%, var(--gold) 55%, var(--healer) 80%, var(--healer) 100%);
  opacity:0.28;
}
@media (max-width:720px){ .spine{display:none;} }

section.chapter{
  position:relative;
  padding:56px 0 40px 0;
  margin-left:34px;
  border-bottom:1px solid var(--line);
}
@media (max-width:720px){ section.chapter{margin-left:0;} }

section.chapter::before{
  content:'';
  position:absolute;
  left:-40px;
  top:64px;
  width:12px; height:12px;
  border-radius:50%;
  background:var(--dot-color, var(--ink));
  box-shadow:0 0 0 4px var(--paper);
  transition: box-shadow .4s ease, transform .4s ease;
}
@media (max-width:720px){ section.chapter::before{display:none;} }

.chapter-num{
  font-family:'IBM Plex Mono', monospace;
  font-size:0.75rem;
  color:var(--dot-color, var(--ink-soft));
  letter-spacing:0.1em;
}
.chapter h2{
  font-size:clamp(1.5rem, 3vw, 2rem);
  margin-top:8px;
  color:var(--ink);
}
.chapter .kicker{
  color:var(--dot-color, var(--patogen));
  font-family:'Fraunces', serif;
  font-style:italic;
  font-weight:500;
}
.chapter h3{
  font-size:1.15rem;
  margin-top:34px;
  margin-bottom:10px;
  color:var(--dot-color, var(--ink));
}
.chapter p{ margin:0 0 14px 0; color:var(--ink); }
.chapter ul{ margin:0 0 14px 0; padding-left:20px; }
.chapter li{ margin-bottom:10px; }
.chapter li strong{ color:var(--dot-color, var(--ink)); }

#ch1{ --dot-color: var(--patogen); }
#ch2{ --dot-color: var(--gold); }
#ch3{ --dot-color: var(--healer); }

.fact-row{
  display:grid;
  grid-template-columns:repeat(2,1fr);
  gap:14px;
  margin:20px 0 28px;
}
@media (max-width:560px){ .fact-row{grid-template-columns:1fr;} }
.fact{
  border:1px solid var(--line);
  border-radius:10px;
  padding:14px 16px;
  background:rgba(255,255,255,0.35);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}
.fact:hover{
  transform:translateY(-4px);
  border-color:var(--dot-color, var(--ink));
  box-shadow:0 10px 22px -14px rgba(27,36,32,0.35);
}
.fact .label{
  font-family:'IBM Plex Mono', monospace;
  font-size:0.66rem;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--ink-soft);
  display:block;
  margin-bottom:5px;
}
.fact .val{ font-size:0.98rem; }

.example-card{
  border-left:3px solid var(--dot-color, var(--ink));
  padding:14px 0 6px 18px;
  margin:18px 0;
  transition: transform .3s ease, border-color .3s ease;
}
.example-card:hover{
  transform:translateX(6px);
}
.example-card .name{
  font-family:'Fraunces', serif;
  font-weight:600;
  font-size:1.05rem;
  margin-bottom:6px;
}

/* images */
.icon-illus{
  width:96px;
  height:auto;
  display:block;
  margin-bottom:10px;
}
figure.micrograph{
  margin:24px 0 30px;
  padding:0;
}
figure.micrograph img{
  width:100%;
  max-width:420px;
  display:block;
  border-radius:10px;
  border:1px solid var(--line);
}
figure.micrograph figcaption{
  font-family:'IBM Plex Mono', monospace;
  font-size:0.68rem;
  color:var(--ink-soft);
  margin-top:8px;
  letter-spacing:0.02em;
}
figure.illus-figure img{
  max-width:320px;
  background:rgba(255,255,255,0.4);
  padding:16px;
}

/* tag hover */
.tag{ transition: transform .2s ease, background .2s ease, border-color .2s ease; }
.tag:hover{
  transform:translateY(-2px) scale(1.03);
  border-color:var(--patogen);
  background:rgba(255,255,255,0.5);
}

/* ---------- CONCLUSION ---------- */
.finale{
  position:relative;
  padding:70px 0 90px;
  background:linear-gradient(120deg, var(--patogen-deep) 0%, var(--patogen) 30%, var(--gold) 50%, var(--healer) 70%, var(--healer-deep) 100%);
  background-size:220% 220%;
  color:#F3EFE4;
  margin-top:20px;
  animation: gradientDrift 14s ease-in-out infinite;
}
.finale .wrap{ position:relative; }
.finale .eyebrow{ color:rgba(243,239,228,0.8); }
.finale h2{
  color:#fff;
  font-size:clamp(1.7rem, 4vw, 2.3rem);
  margin-top:14px;
  max-width:22ch;
}
.finale p{
  max-width:62ch;
  margin-top:18px;
  font-size:1.05rem;
  color:rgba(243,239,228,0.92);
}
.finale .duo{
  display:flex;
  gap:14px;
  margin-top:34px;
  font-family:'IBM Plex Mono', monospace;
  font-size:0.78rem;
  letter-spacing:0.05em;
}
.finale .duo span{
  border:1px solid rgba(243,239,228,0.5);
  border-radius:100px;
  padding:6px 14px;
  transition: transform .25s ease, background .25s ease;
}
.finale .duo span:hover{
  transform:translateY(-3px);
  background:rgba(243,239,228,0.14);
}

footer{
  padding:26px 28px 46px;
  text-align:center;
  font-family:'IBM Plex Mono', monospace;
  font-size:0.72rem;
  color:var(--ink-soft);
  max-width:880px;
  margin:0 auto;
  line-height:1.6;
}

/* ---------- ANIMATION: hero capsid ---------- */
.capsid-hero{
  transform-origin:50% 50%;
  animation: capsidFloat 7s ease-in-out infinite;
  transition: transform 0.15s ease-out;
  will-change: transform;
}
@keyframes capsidFloat{
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-10px) rotate(2deg); }
}
.capsid-hero .fiber{
  animation: fiberPulse 2.6s ease-in-out infinite;
  transform-origin:center;
}
.capsid-hero .fiber:nth-child(2){ animation-delay:.15s; }
.capsid-hero .fiber:nth-child(3){ animation-delay:.3s; }
.capsid-hero .fiber:nth-child(4){ animation-delay:.45s; }
.capsid-hero .fiber:nth-child(5){ animation-delay:.6s; }
.capsid-hero .fiber:nth-child(6){ animation-delay:.75s; }
.capsid-hero .fiber:nth-child(7){ animation-delay:.9s; }
.capsid-hero .fiber:nth-child(8){ animation-delay:1.05s; }
@keyframes fiberPulse{
  0%, 100% { opacity:0.55; }
  50% { opacity:1; }
}

/* ---------- ANIMATION: reveal on scroll ---------- */
.reveal{
  opacity:0;
  transform:translateY(28px);
  transition:opacity .8s cubic-bezier(.2,.7,.3,1), transform .8s cubic-bezier(.2,.7,.3,1);
}
.reveal.in-view{
  opacity:1;
  transform:translateY(0);
}
.reveal-stagger > *{
  opacity:0;
  transform:translateY(20px);
  transition:opacity .7s ease, transform .7s ease;
}
.reveal-stagger.in-view > *{
  opacity:1;
  transform:translateY(0);
}
.reveal-stagger.in-view > *:nth-child(1){ transition-delay:.05s; }
.reveal-stagger.in-view > *:nth-child(2){ transition-delay:.18s; }
.reveal-stagger.in-view > *:nth-child(3){ transition-delay:.31s; }
.reveal-stagger.in-view > *:nth-child(4){ transition-delay:.44s; }

section.chapter.in-view::before{
  animation: dotPulse 1.6s ease-out 1;
}
@keyframes dotPulse{
  0% { box-shadow:0 0 0 4px var(--paper), 0 0 0 4px var(--dot-color, var(--ink)); transform:scale(1); }
  60% { box-shadow:0 0 0 4px var(--paper), 0 0 0 12px transparent; transform:scale(1.35); }
  100% { box-shadow:0 0 0 4px var(--paper), 0 0 0 4px transparent; transform:scale(1); }
}

/* spine progress fill drawn as you scroll */
.spine-fill{
  position:absolute;
  left:28px;
  top:0;
  width:2px;
  height:0%;
  background:linear-gradient(180deg, var(--patogen) 0%, var(--patogen) 30%, var(--gold) 55%, var(--healer) 80%, var(--healer) 100%);
  box-shadow:0 0 8px 1px rgba(31,122,108,0.35);
  transition:height .12s linear;
}
@media (max-width:720px){ .spine-fill{display:none;} }

@keyframes gradientDrift{
  0%, 100% { background-position:0% 50%; }
  50% { background-position:100% 50%; }
}

@media (prefers-reduced-motion: reduce){
  .capsid-hero,
  .capsid-hero .fiber,
  .finale,
  section.chapter.in-view::before{
    animation:none !important;
  }
  .reveal, .reveal-stagger > *{
    opacity:1 !important;
    transform:none !important;
    transition:none !important;
  }
  .spine-fill{ transition:none; }
  .fact:hover, .tag:hover, .example-card:hover, .finale .duo span:hover{
    transform:none;
  }
}