/* ==========================================================================
   撮られ方図鑑 / TORAREKATA ZUKAN
   共通スタイル
   - 学術図鑑の骨格 × 和紙のような温度感
   ========================================================================== */

/* ---------- Tokens ---------- */
:root {
  /* Surface — 和紙のような生成りの白 */
  --paper:        #faf7f1;     /* メインの紙地 */
  --paper-warm:   #f3ede1;     /* セクション差し色 */
  --paper-deep:   #ece4d3;     /* 奥行きを出す陰 */
  --rule:         #d9cfb8;     /* 罫線 */
  --rule-soft:    #e8dfc9;

  /* Ink — チャコールの本文 */
  --ink:          #1f1c17;     /* 主見出し / 強い本文 */
  --ink-body:     #2c2820;
  --ink-soft:     #5b5446;
  --ink-faint:    #8a8270;

  /* Accent — 藍 + 朱の差し */
  --indigo:       #1e3a5f;
  --indigo-deep:  #142745;
  --indigo-soft:  #3d5a82;
  --vermilion:    #b03a2e;     /* 章番号・極小面積のみ */

  /* Type */
  --serif-jp: "Shippori Mincho B1", "Noto Serif JP", "Hiragino Mincho ProN", "ヒラギノ明朝 ProN", "游明朝", serif;
  --sans-jp:  "Noto Sans JP", "Hiragino Kaku Gothic ProN", "ヒラギノ角ゴ ProN", -apple-system, sans-serif;
  --serif-en: "Cormorant Garamond", "EB Garamond", Georgia, serif;
  --mono:     "JetBrains Mono", ui-monospace, monospace;

  /* Rhythm */
  --max:      1200px;
  --read:     720px;
  --gutter:   clamp(20px, 4vw, 48px);
}

/* ---------- Reset ---------- */
*,*::before,*::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }

html { scroll-behavior: smooth; }
body {
  background: var(--paper);
  color: var(--ink-body);
  font-family: var(--sans-jp);
  font-size: 17px;
  line-height: 1.85;
  font-feature-settings: "palt" 1;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* 紙のテクスチャ — ごく薄く */
body::before {
  content: "";
  position: fixed; inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    radial-gradient(circle at 20% 30%, rgba(180,160,120,0.04) 0, transparent 50%),
    radial-gradient(circle at 80% 70%, rgba(180,160,120,0.04) 0, transparent 50%);
}

main, header, footer, section { position: relative; z-index: 1; }

/* ---------- Type ---------- */
h1,h2,h3,h4 { font-family: var(--serif-jp); color: var(--ink); font-weight: 500; letter-spacing: 0.02em; }
.en { font-family: var(--serif-en); font-style: italic; letter-spacing: 0.04em; font-weight: 400; }
.tab { font-family: var(--serif-en); font-feature-settings: "tnum" 1; letter-spacing: 0.08em; }
.eyebrow {
  font-family: var(--serif-en);
  font-size: 12px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--ink-faint);
  font-style: normal;
}

/* ---------- Layout ---------- */
.container { max-width: var(--max); margin: 0 auto; padding: 0 var(--gutter); }
.read     { max-width: var(--read); margin: 0 auto; padding: 0 var(--gutter); }

/* ---------- Header / nav ---------- */
.site-head {
  position: sticky; top: 0; z-index: 50;
  background: rgba(250,247,241,0.88);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--rule-soft);
}
.site-head-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 14px var(--gutter);
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px;
}
.brand {
  display: flex; align-items: baseline; gap: 14px;
  text-decoration: none; color: var(--ink);
}
.brand::before {
  content: "";
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
  background: url("../img/site-icon.svg") center / contain no-repeat;
}
.brand-mark {
  font-family: var(--serif-jp);
  font-size: 19px;
  letter-spacing: 0.12em;
}
.brand-en {
  font-family: var(--serif-en);
  font-size: 11px;
  letter-spacing: 0.32em;
  color: var(--ink-faint);
  text-transform: uppercase;
}
.nav { display: flex; gap: 28px; align-items: center; }
.nav a {
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--ink-soft);
  position: relative;
  padding: 6px 0;
  transition: color .25s ease;
}
.nav a:hover { color: var(--indigo); }
.nav a::after {
  content: "";
  position: absolute; left: 0; right: 0; bottom: -2px;
  height: 1px; background: var(--indigo);
  transform: scaleX(0); transform-origin: left;
  transition: transform .3s ease;
}
.nav a:hover::after { transform: scaleX(1); }
.nav-toggle { display: none; background: none; border: 0; padding: 8px; cursor: pointer; }
.nav-toggle span { display: block; width: 22px; height: 1px; background: var(--ink); margin: 5px 0; transition: all .25s; }

@media (max-width: 760px) {
  .nav { display: none; }
  .nav.open {
    display: flex; flex-direction: column;
    position: absolute; top: 100%; left: 0; right: 0;
    background: var(--paper);
    padding: 20px var(--gutter);
    border-bottom: 1px solid var(--rule-soft);
    gap: 18px; align-items: flex-start;
  }
  .nav-toggle { display: block; }
}

/* ---------- Footer ---------- */
.site-foot {
  margin-top: 120px;
  padding: 60px var(--gutter) 40px;
  border-top: 1px solid var(--rule);
  background: var(--paper-warm);
}
.site-foot-inner {
  max-width: var(--max); margin: 0 auto;
  display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 48px;
}
.site-foot h4 {
  font-size: 13px;
  letter-spacing: 0.2em;
  margin: 0 0 16px;
  color: var(--ink-faint);
  font-weight: 500;
}
.site-foot ul { list-style: none; padding: 0; margin: 0; }
.site-foot li { margin: 6px 0; font-size: 14px; }
.site-foot a {
  display: inline-block;
  padding: 2px 0;
  border-bottom: 1px solid transparent;
  transition: color .2s, border-color .2s;
}
.site-foot a:hover { color: var(--indigo); border-bottom-color: var(--indigo); }
.site-foot a:focus-visible { outline: 2px solid var(--indigo); outline-offset: 3px; }
.nav a:focus-visible { outline: 2px solid var(--indigo); outline-offset: 4px; }
.site-foot .copyright {
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--rule-soft);
  font-size: 12px; color: var(--ink-faint);
  letter-spacing: 0.1em;
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 16px;
}
.foot-brand { font-family: var(--serif-jp); font-size: 22px; letter-spacing: 0.1em; color: var(--ink); margin: 0 0 8px; }
.foot-tagline { color: var(--ink-soft); font-size: 13px; max-width: 32ch; line-height: 1.7; }
@media (max-width: 760px) {
  .site-foot-inner { grid-template-columns: 1fr; gap: 32px; }
}

/* ---------- Language toggle ---------- */
.lang-toggle {
  display: inline-flex; align-items: center; gap: 5px;
  margin-left: 8px; padding-left: 14px;
  border-left: 1px solid var(--rule);
  font-family: var(--serif-en);
  font-size: 11px; letter-spacing: 0.2em; text-transform: uppercase;
}
.lang-toggle__globe { width: 13px; height: 13px; opacity: .55; vertical-align: middle; }
.lang-toggle__active { color: var(--ink); font-weight: 500; }
.lang-toggle__sep { color: var(--ink-faint); }
.lang-toggle__link {
  color: var(--ink-faint); text-decoration: none;
  padding: 3px 5px; border: 1px solid var(--rule);
  transition: color .2s, border-color .2s;
}
.lang-toggle__link:hover { color: var(--indigo); border-color: var(--indigo); }
.lang-toggle__link:focus-visible { outline: 2px solid var(--indigo); outline-offset: 2px; }
@media (max-width: 760px) {
  .lang-toggle { margin-left: 0; padding-left: 0; border-left: none; }
}
.foot-lang-toggle {
  display: flex; align-items: center; gap: 5px; margin-top: 12px;
  font-family: var(--serif-en); font-size: 11px;
  letter-spacing: 0.2em; text-transform: uppercase; color: var(--ink-faint);
}
.foot-lang-toggle .lang-toggle__globe { width: 12px; height: 12px; opacity: .45; }
.foot-lang-toggle__active { color: var(--ink); font-weight: 500; }
.foot-lang-toggle__link {
  color: var(--ink-faint); text-decoration: none;
  padding: 2px 5px; border: 1px solid var(--rule);
  transition: color .2s, border-color .2s;
}
.foot-lang-toggle__link:hover { color: var(--indigo); border-color: var(--indigo); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 14px 28px;
  font-family: var(--sans-jp);
  font-size: 14px;
  letter-spacing: 0.1em;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--paper);
  cursor: pointer;
  transition: all .25s ease;
}
.btn:hover { background: var(--indigo); border-color: var(--indigo); }
.btn--ghost {
  background: transparent;
  color: var(--ink);
}
.btn--ghost:hover { background: var(--ink); color: var(--paper); }
.btn .arrow { transition: transform .25s; }
.btn:hover .arrow { transform: translateX(4px); }

/* ---------- Index numerals (図鑑番号) ---------- */
.idx {
  font-family: var(--serif-en);
  font-feature-settings: "tnum" 1, "lnum" 1;
  font-style: italic;
  color: var(--vermilion);
  font-weight: 400;
}

/* ---------- Decorative rule ---------- */
.rule-thick { height: 1px; background: var(--ink); border: 0; margin: 0; }
.rule-thin  { height: 1px; background: var(--rule); border: 0; margin: 0; }
.rule-double {
  border: 0;
  border-top: 1px solid var(--ink);
  border-bottom: 1px solid var(--ink);
  height: 5px;
  background: transparent;
}

/* ---------- Reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .9s ease, transform .9s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- Tweaks panel ---------- */
.tweaks {
  position: fixed; right: 18px; bottom: 18px;
  width: 280px;
  background: var(--paper);
  border: 1px solid var(--ink);
  padding: 18px 20px 20px;
  font-family: var(--sans-jp);
  font-size: 13px;
  z-index: 100;
  display: none;
  box-shadow: 0 20px 40px -20px rgba(20,15,5,0.25);
}
.tweaks.show { display: block; }
.tweaks h5 {
  font-family: var(--serif-en);
  font-style: italic;
  font-size: 14px;
  letter-spacing: 0.1em;
  margin: 0 0 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--rule);
  color: var(--ink);
  font-weight: 500;
  display: flex; justify-content: space-between; align-items: baseline;
}
.tweaks h5 small { font-family: var(--sans-jp); font-style: normal; font-size: 10px; letter-spacing: 0.18em; color: var(--ink-faint); }
.tweak-row { margin: 12px 0; }
.tweak-row label {
  display: block;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--ink-faint);
  margin-bottom: 6px;
}
.tweak-row .opts { display: flex; gap: 6px; flex-wrap: wrap; }
.tweak-row .opts button {
  flex: 1;
  padding: 7px 10px;
  background: transparent;
  border: 1px solid var(--rule);
  color: var(--ink-soft);
  font-family: var(--sans-jp);
  font-size: 12px;
  cursor: pointer;
  transition: all .2s;
}
.tweak-row .opts button:hover { border-color: var(--ink-soft); }
.tweak-row .opts button.active {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}

/* ---------- Theme variants (Tweaks) ---------- */
body.theme-sumi { --indigo: #2c3e50; --indigo-deep: #1c2833; --indigo-soft: #4a6075; }
body.theme-indigo-vermilion { /* default */ }
body.theme-indigo { --vermilion: var(--indigo); }