/*
  V4 — 光脈の旅 / The Luminous Thread
  Clean rewrite of the V3 concept: one coherent ruleset instead of layered
  patches. #main-nav now lives as a sibling of <header> in the HTML (not a
  child), so position:fixed is never trapped inside an ancestor with
  backdrop-filter/transform — the bug fixed in V3 can't recur here by
  construction. The signature addition is a scroll-linked glow that travels
  down the contents rail as you read each page, echoing フォリオ's light.
*/

:root,
html[data-theme="a"],
html[data-theme="b"],
html[data-theme="c"]{
  --bg:#07100d;
  --surface:#0d1a15;
  --ink:#f1f0e7;
  --muted:#9eaea4;
  --accent:#a9d8bd;
  --accent2:#d8b468;
  --line:rgba(220,232,221,.14);
  --shadow:0 34px 100px rgba(0,0,0,.58);
  --radius:0;
  --display:"Elucia Celestial","Cormorant Garamond","Noto Serif JP",serif;
  --rail-w:250px;
}
html[lang="zh-Hant"]{
  --display:"Elucia TC Elegant","Noto Serif TC","Noto Serif JP",serif;
  --body:"Elucia TC Elegant","Noto Serif TC","Noto Serif JP",serif;
}

body{
  background:
    radial-gradient(circle at 78% 6%,rgba(216,180,104,.09),transparent 25rem),
    radial-gradient(circle at 12% 55%,rgba(169,216,189,.06),transparent 32rem),
    var(--bg);
}

/* ---------- background color variants ---------- */
html[data-bg="1"]{--bg:#07100d;--surface:#0d1a15}
html[data-bg="2"]{--bg:#070912;--surface:#0e1220}
html[data-bg="3"]{--bg:#130a0d;--surface:#1f1116}
html[data-bg="4"]{--bg:#0a0a0b;--surface:#151516}
html[data-bg="5"]{--bg:#061014;--surface:#0d1e24}
html[data-bg="6"]{--bg:#0d0a14;--surface:#181120}
html[data-bg="7"]{--bg:#120d05;--surface:#1e160a}
html[data-bg="8"]{--bg:#050f0b;--surface:#0c1e16}
html[data-bg="9"]{--bg:#0b0b0c;--surface:#161617}
html[data-bg="10"]{--bg:#140f0a;--surface:#211810}

.concept-switcher{
  position:fixed;right:1rem;bottom:1rem;z-index:35;display:flex;gap:.4rem;align-items:center;
  padding:.5rem;background:rgba(5,12,9,.92);border:1px solid var(--line);
  box-shadow:var(--shadow);backdrop-filter:blur(14px);
}
.concept-switcher>span{padding:0 .3rem 0 .1rem;color:var(--muted);font:600 .58rem/1 var(--display);letter-spacing:.18em}
.concept-switcher button{
  width:22px;height:22px;padding:0;border-radius:50%;cursor:pointer;
  border:2px solid transparent;box-shadow:inset 0 0 0 1px rgba(255,255,255,.12);
}
.concept-switcher button[aria-pressed="true"]{border-color:var(--accent2)}
.concept-switcher button:hover{border-color:var(--accent)}
@media(max-width:680px){
  .concept-switcher{right:.5rem;bottom:.5rem;flex-wrap:wrap;max-width:calc(100vw - 1rem)}
  .concept-switcher>span{display:none}
}

/* ---------- header ---------- */
.site-header{
  min-height:76px;padding:0 clamp(1.2rem,4vw,4rem) 0 clamp(1.2rem,3vw,1.7rem);
  background:linear-gradient(180deg,rgba(4,9,7,.94),rgba(4,9,7,.7));
  border-bottom:1px solid rgba(216,180,104,.17);
}
.brand-mark{border-color:var(--accent2);box-shadow:0 0 26px rgba(216,180,104,.18)}
.brand b{font-size:.9rem}
.brand small{color:var(--accent);letter-spacing:.24em}
.header-actions{margin-left:auto}
.menu-button{display:none;border-color:rgba(216,180,104,.4);color:var(--accent2);letter-spacing:.12em}
.lang-switch{border-color:rgba(220,232,221,.18)}
.lang-switch button[aria-pressed="true"]{background:var(--accent2);color:#171108}

/* ---------- contents rail (#main-nav, sibling of header) ---------- */
#main-nav{
  display:flex;flex-direction:column;align-items:stretch;gap:0;
  position:fixed;top:76px;left:0;bottom:0;z-index:30;width:var(--rail-w);
  padding:2.6rem 1.25rem 1rem;background:rgba(5,12,9,.97);
  border-right:1px solid rgba(216,180,104,.2);overflow:hidden;
  counter-reset:nav-item;
}
#main-nav::before{
  content:"CONTENTS";display:block;margin:0 0 1.1rem .45rem;
  color:var(--accent2);font:400 .58rem/1 var(--display);letter-spacing:.32em;
}
#main-nav a{
  display:grid;grid-template-columns:1.65rem 1fr;align-items:center;
  padding:.55rem .45rem;color:#bac7bf;font-size:.79rem;line-height:1.25;
}
#main-nav a::before{
  content:counter(nav-item,decimal-leading-zero);counter-increment:nav-item;
  color:rgba(216,180,104,.48);font:400 .55rem/1 "Elucia Road",serif;
}
#main-nav a:hover{color:var(--ink);background:rgba(169,216,189,.035)}
#main-nav a[aria-current="page"]{
  color:var(--accent);background:linear-gradient(90deg,rgba(169,216,189,.1),transparent);
  box-shadow:inset 2px 0 var(--accent);
}
#main-nav a[aria-current="page"]::before{color:var(--accent2)}
#main-nav a[aria-current="page"]::after{display:none} /* clear site.css underline */

/* the thread: a track down the rail's left edge, lit progressively by scroll */
.thread-rail{position:absolute;left:.5rem;top:2.6rem;bottom:1rem;width:2px;background:var(--line)}
.thread-rail::after{
  content:"";position:absolute;left:0;top:0;width:100%;
  height:var(--thread-progress,0%);
  background:linear-gradient(180deg,var(--accent),var(--accent2));
  box-shadow:0 0 12px 1px rgba(169,216,189,.5);
  transition:height .12s linear;
}
.thread-charm{
  position:absolute;left:calc(.5rem - 4px);top:calc(2.6rem + var(--thread-progress,0%) - 5px);
  width:10px;height:10px;border-radius:50%;background:var(--accent);
  box-shadow:0 0 0 4px rgba(169,216,189,.1),0 0 16px rgba(169,216,189,.75);
  transition:top .12s linear;
}

main,footer{margin-left:var(--rail-w)}
.page{width:min(1180px,calc(100% - 3rem));padding-left:1rem}
.hero{padding-left:clamp(3rem,6vw,7rem);padding-right:clamp(2rem,5vw,6rem)}
footer{padding-left:clamp(2rem,5vw,5rem);background:#050b08;border-color:var(--line)}

/* ---------- hero ---------- */
.hero{
  position:relative;grid-template-columns:minmax(310px,.88fr) 1.12fr;
  width:100%;max-width:none;min-height:100vh;margin:0;padding:8rem clamp(2rem,7vw,8rem) 5rem clamp(4rem,9vw,9rem);
  gap:clamp(3rem,8vw,8rem);
}
.hero::before{
  content:"VOLUME 01";position:absolute;right:-.06em;top:.43em;z-index:-1;
  color:rgba(216,180,104,.045);font-family:"Elucia Celestial",serif;
  font-size:clamp(7rem,22vw,22rem);line-height:.8;letter-spacing:-.05em;white-space:nowrap;
}
.hero::after{
  content:"THE LUMINOUS THREAD";position:absolute;right:clamp(2rem,6vw,6rem);bottom:2rem;
  color:var(--muted);font:400 .58rem/1 "Elucia Celestial",serif;letter-spacing:.4em;
}
.hero-cover{max-width:460px}
.hero-cover::before{display:none}
.hero-cover img{
  max-height:76vh;filter:saturate(.9) contrast(1.04);
  border:1px solid rgba(216,180,104,.28);
  box-shadow:0 45px 120px rgba(0,0,0,.65),0 0 0 10px rgba(216,180,104,.025);
}
.hero-copy{max-width:720px}
.hero-copy .eyebrow{color:var(--accent2);letter-spacing:.34em}
.hero-copy h1{font-size:clamp(4.7rem,12vw,11rem);color:var(--ink);text-shadow:0 0 70px rgba(169,216,189,.1)}
.hero-copy h1 span{margin-top:.55em;color:var(--accent);font-size:.22em;letter-spacing:.2em}
.hero-copy .tagline{max-width:610px;margin:2.4rem 0;color:#bdc8c0;font-size:clamp(.95rem,1.5vw,1.12rem)}

/* ---------- shared components ---------- */
.button{border-color:rgba(216,180,104,.55);letter-spacing:.06em;transition:.25s ease}
.button.primary{background:var(--accent2);border-color:var(--accent2);color:#171108}
.button:hover{transform:translateY(-2px);border-color:var(--accent);color:var(--accent)}
.button.primary:hover{background:var(--accent);color:#07100d}
.section-head{padding-bottom:1.5rem;border-bottom:1px solid var(--line)}
.section-head .page-title{color:var(--ink);font-size:clamp(3rem,7vw,6.7rem)}
.section-number,.eyebrow{color:var(--accent2)}
.story-grid img,.feature-image,.character-sheet img,.author-layout img{border:1px solid rgba(216,180,104,.2);filter:saturate(.83)}
.quote{padding-left:1.4rem;border-left:2px solid var(--accent2);border-block:0;color:var(--accent)}
.episode-list,.episode-list a{border-color:var(--line)}
.episode-list a{transition:.25s}
.episode-list a:hover{background:rgba(169,216,189,.05);color:var(--accent)}
.ep-page .ep-body{max-width:720px;margin:0 auto;font-size:1.02rem;line-height:2}
.ep-page .ep-body p{margin:0 0 1.5rem;white-space:pre-line}
.ep-pending{max-width:720px;margin:0 auto 2rem;padding:.8rem 1rem;border:1px solid var(--line);color:var(--muted);font-size:.8rem}
.ep-pager{display:flex;justify-content:space-between;align-items:center;gap:1rem;max-width:720px;margin:4rem auto 0;padding-top:2rem;border-top:1px solid var(--line)}
.ep-pager a{color:var(--muted);font-size:.85rem;max-width:32%}
.ep-pager a:hover{color:var(--accent)}
.ep-pager-index{color:var(--accent2)!important;text-align:center}
@media(max-width:680px){.ep-pager{flex-direction:column;align-items:stretch;text-align:center}.ep-pager a{max-width:none}}
.character-names div,.item-card,.link-card,.font-sample,.gallery-tile{background:linear-gradient(145deg,rgba(18,34,27,.92),rgba(10,23,18,.92));border-color:var(--line)}
.gallery img{filter:saturate(.8);transition:.5s ease}
.gallery figure:hover img{filter:saturate(1);transform:scale(1.025)}
.item-card img{filter:saturate(.76)}
.bridge figure{border:1px solid var(--line)}
.link-card{transition:.3s ease}
.link-card:hover{border-color:rgba(216,180,104,.5);transform:translateY(-4px);box-shadow:0 24px 60px rgba(0,0,0,.28)}
.link-icon{box-shadow:0 0 30px rgba(216,180,104,.08)}
.font-sample strong{color:var(--accent)}

/* ---------- responsive ---------- */
@media(max-width:900px){
  .hero{grid-template-columns:1fr;padding:7rem 2rem 5rem 2rem}
  .hero-cover{max-width:340px}
  .hero-copy h1{font-size:clamp(4.2rem,20vw,8rem)}
  .hero::after{display:none}
}
@media(max-width:680px){
  :root{--rail-w:0px}
  .brand small{display:none}
  .lang-switch button{padding:.3rem .38rem}
  .site-header{padding-right:.7rem}
  .menu-button{display:block}
  #main-nav{
    display:none;top:auto;left:0;right:0;bottom:auto;width:auto;height:auto;
    position:fixed;inset:70px 0 auto 0;padding:1.5rem 1.25rem 1.5rem 2.5rem;
    max-height:calc(100vh - 70px);overflow:auto;border-right:0;border-bottom:1px solid rgba(216,180,104,.2);
  }
  #main-nav.open{display:flex}
  .thread-rail,.thread-charm{left:.9rem}
  main,footer{margin-left:0}
  .page{width:calc(100% - 1.5rem);padding-left:0}
  .hero{padding-left:1.25rem;padding-right:1rem}
  footer{padding-left:1.5rem}
}
@media(min-width:681px) and (max-height:720px){
  #main-nav{padding-top:2rem}
  #main-nav a{padding:.4rem .45rem;font-size:.73rem}
}
@media(prefers-reduced-motion:reduce){.thread-rail::after,.thread-charm{transition:none}}

/* ---------- SNS page ---------- */
.sns-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:1.5rem}
.sns-card{
  display:grid;grid-template-columns:150px 1fr;gap:1.5rem;align-items:center;
  padding:1.8rem;border:1px solid var(--line);
  background:linear-gradient(145deg,rgba(18,34,27,.92),rgba(10,23,18,.92));
}
.sns-qr{padding:.6rem;background:#f1f0e7;line-height:0}
.sns-qr img{width:100%;display:block}
.sns-info .eyebrow{color:var(--accent2);letter-spacing:.24em;font-size:.68rem}
.sns-info h2{margin:.3rem 0 .8rem;font-family:var(--display);font-weight:600;font-size:1.5rem;color:var(--ink)}
.sns-info p{margin:0 0 1.2rem;color:var(--muted);font-size:.85rem;line-height:1.7}
@media(max-width:680px){
  .sns-grid{grid-template-columns:1fr}
  .sns-card{grid-template-columns:110px 1fr;padding:1.3rem;gap:1rem}
}
.link-card.is-pending{opacity:.55;cursor:default}
.sns-card.is-pending{opacity:.55}
.sns-qr-empty{display:grid;place-items:center;aspect-ratio:1;color:#07100d;font:500 .68rem/1.3 var(--ui,sans-serif);text-align:center;padding:.5rem}
.button.is-disabled{display:inline-block;border-color:var(--line);color:var(--muted);cursor:default}
.item-card.img-missing,.gallery figure.img-missing{display:none}
.link-grid-single{grid-template-columns:minmax(260px,420px);justify-content:start}
.font-dl{align-self:flex-start;margin-top:1.5rem;min-width:auto;padding:.6rem 1.1rem;font-size:.78rem}
.link-note{margin-top:1.5rem;color:var(--muted);font-size:.85rem}
.link-note a{color:var(--accent2);border-bottom:1px solid var(--accent2)}
.link-note a:hover{color:var(--accent)}