/* 18合同会社 — Layout: left-anchored editorial column, classification strip on top,
   redaction bars as the recurring motif (public tier of a confidential company). */
:root {
  --paper: #e5e3de;
  --paper-2: #dcd9d3;
  --ink: #1d1815;
  --mute: #6b625b;
  --logo: #534741;
  --logo-2: #736357;
  --redact: #1d1815;
  --redact-fg: #e5e3de;
  --seal: #93391f;
  --line: rgba(29, 24, 21, .16);

  --f-display: "Shippori Mincho B1", "Hiragino Mincho ProN", "Yu Mincho", serif;
  --f-body: "Zen Kaku Gothic New", "Hiragino Sans", "Yu Gothic", system-ui, sans-serif;
  --f-mark: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --f-latin: "Cormorant Garamond", "Athelas", Georgia, serif;

  --step--1: .8125rem;
  --step-0: 1rem;
  --step-1: 1.25rem;
  --step-2: clamp(1.5rem, 1.2rem + 1.2vw, 2rem);
  --step-3: clamp(2rem, 1.4rem + 2.6vw, 3.25rem);
  --step-4: clamp(2.6rem, 1.2rem + 6.4vw, 6.5rem);

  --gutter: clamp(16px, 4vw, 56px);
  --max: 1240px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #14110f; --paper-2: #1c1815; --ink: #e8e2d9; --mute: #9d938a;
    --logo: #cdbcab; --logo-2: #a8988a; --redact: #e8e2d9; --redact-fg: #14110f;
    --seal: #d3765a; --line: rgba(232, 226, 217, .14); color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #14110f; --paper-2: #1c1815; --ink: #e8e2d9; --mute: #9d938a;
  --logo: #cdbcab; --logo-2: #a8988a; --redact: #e8e2d9; --redact-fg: #14110f;
  --seal: #d3765a; --line: rgba(232, 226, 217, .14); color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font-family: var(--f-body); font-size: var(--step-0); line-height: 1.85;
  letter-spacing: .02em; -webkit-font-smoothing: antialiased;
}
img, svg { max-width: 100%; }
a { color: inherit; }
::selection { background: var(--redact); color: var(--redact-fg); }
:focus-visible { outline: 2px solid var(--seal); outline-offset: 3px; }

/* grain */
body::after {
  content: ""; position: fixed; inset: 0; pointer-events: none; z-index: 100; opacity: .06;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

.wrap { width: 100%; max-width: var(--max); margin-inline: auto; padding-inline: var(--gutter); }

/* ---------- classification strip + header ---------- */
.strip {
  font-family: var(--f-mark); font-size: .6875rem; letter-spacing: .14em; text-transform: uppercase;
  border-bottom: 1px solid var(--line); color: var(--mute);
}
.strip .wrap { display: flex; flex-wrap: wrap; gap: .25rem 1.5rem; justify-content: space-between; padding-block: .45rem; }
.strip b { color: var(--seal); font-weight: 600; }

.site-header {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 50;
  background: color-mix(in srgb, var(--paper) 86%, transparent);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding-block: .8rem; }
.brand { display: flex; align-items: center; gap: .7rem; text-decoration: none; min-width: 0; }
.brand .mark { width: 34px; height: auto; flex: none; }
.brand .type { width: 132px; height: auto; }
.logo-fill { fill: var(--logo); }
.logo-fill-2 { fill: var(--logo-2); }

.nav { display: flex; gap: 1.6rem; font-size: .875rem; }
.nav a { text-decoration: none; position: relative; padding-block: .2rem; }
.nav a::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: 0; height: 1px; background: currentColor;
  transform: scaleX(0); transform-origin: right; transition: transform .35s ease;
}
.nav a:hover::after, .nav a[aria-current="page"]::after { transform: scaleX(1); transform-origin: left; }
.menu-btn {
  display: none; font: inherit; font-family: var(--f-mark); font-size: .75rem; letter-spacing: .12em;
  background: none; border: 1px solid var(--line); color: var(--ink); padding: .4rem .7rem; cursor: pointer;
}
@media (max-width: 820px) {
  .menu-btn { display: block; }
  .nav {
    position: absolute; left: 0; right: 0; top: 100%; flex-direction: column; gap: 0;
    background: var(--paper); border-bottom: 1px solid var(--line); padding: .5rem var(--gutter) 1rem;
  }
  .nav a { padding-block: .7rem; border-bottom: 1px solid var(--line); }
  .nav:not(.open) { display: none; }
}

.progress { position: fixed; left: 0; top: 0; height: 2px; width: 100%; background: var(--seal); transform-origin: left; transform: scaleX(0); z-index: 60; }

/* ---------- hero ---------- */
.hero { position: relative; overflow: hidden; border-bottom: 1px solid var(--line); }
.hero .wrap { display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr); gap: 2rem; align-items: end; padding-block: clamp(3rem, 8vw, 7rem) clamp(2.5rem, 6vw, 5rem); }
.eyebrow { font-family: var(--f-mark); font-size: .75rem; letter-spacing: .18em; text-transform: uppercase; color: var(--mute); display: flex; gap: .8rem; align-items: center; }
.eyebrow::before { content: ""; width: 28px; height: 1px; background: currentColor; }
.hero h1 {
  font-family: var(--f-display); font-weight: 800; font-size: var(--step-4); line-height: 1.12;
  letter-spacing: .01em; margin: 1.2rem 0 1.6rem; text-wrap: balance;
}
.hero .lead { max-width: 34em; color: var(--mute); margin: 0; }
.hero .latin { font-family: var(--f-latin); font-style: italic; font-size: var(--step-2); color: var(--logo-2); margin: 0 0 .4rem; letter-spacing: .01em; }
.hero-mark { justify-self: end; width: min(100%, 420px); }
.hero-mark path { fill: var(--logo); stroke: var(--logo); stroke-width: 3; }

/* redaction-sweep: text is readable before and after; a bar passes over it once */
.sweep { position: relative; display: inline-block; }
.sweep::after {
  content: ""; position: absolute; inset: .08em -.06em; background: var(--redact);
  transform: scaleX(0); transform-origin: left;
  animation: sweep 1.3s cubic-bezier(.7, 0, .2, 1) both; animation-delay: var(--d, .2s);
}
@keyframes sweep {
  0% { transform: scaleX(0); transform-origin: left; }
  45% { transform: scaleX(1); transform-origin: left; }
  55% { transform: scaleX(1); transform-origin: right; }
  100% { transform: scaleX(0); transform-origin: right; }
}
.draw path { stroke-dasharray: 4200; stroke-dashoffset: 0; animation: draw 2.4s ease both .3s; }
@keyframes draw { from { stroke-dashoffset: 4200; fill-opacity: 0; } 70% { fill-opacity: 0; } to { stroke-dashoffset: 0; fill-opacity: 1; } }

@media (max-width: 820px) {
  .hero .wrap { grid-template-columns: 1fr; }
  .hero-mark { justify-self: start; width: 140px; order: -1; }
}

/* ---------- ticker ---------- */
.ticker { overflow: hidden; border-bottom: 1px solid var(--line); font-family: var(--f-mark); font-size: .75rem; letter-spacing: .2em; text-transform: uppercase; color: var(--mute); }
.ticker-track { display: flex; width: max-content; animation: tick 48s linear infinite; }
.ticker-track span { padding: .8rem 1.6rem; white-space: nowrap; }
.ticker-track span:nth-child(3n+1) { color: var(--seal); }
@keyframes tick { to { transform: translateX(-50%); } }

/* ---------- sections ---------- */
.section { padding-block: clamp(3.5rem, 9vw, 7.5rem); border-bottom: 1px solid var(--line); }
.sec-head { display: grid; grid-template-columns: minmax(0, 220px) minmax(0, 1fr); gap: 1rem 3rem; margin-bottom: clamp(2rem, 5vw, 3.5rem); }
.sec-label { font-family: var(--f-mark); font-size: .75rem; letter-spacing: .16em; text-transform: uppercase; color: var(--mute); padding-top: .9rem; }
.sec-title { font-family: var(--f-display); font-weight: 700; font-size: var(--step-3); line-height: 1.3; margin: 0; text-wrap: balance; }
.prose { max-width: 38em; }
.prose p { margin: 0 0 1.2em; }
@media (max-width: 820px) { .sec-head { grid-template-columns: 1fr; } .sec-label { padding-top: 0; } }

.offset { margin-left: calc(220px + 3rem); }
@media (max-width: 820px) { .offset { margin-left: 0; } }

/* domains list with redacted details */
.domains { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--ink); }
.domain {
  display: grid; grid-template-columns: minmax(0, 220px) minmax(0, 1fr) minmax(0, 300px); gap: .6rem 3rem;
  padding-block: 1.6rem; border-bottom: 1px solid var(--line); align-items: baseline;
}
.domain .code { font-family: var(--f-mark); font-size: .75rem; color: var(--mute); letter-spacing: .1em; }
.domain h3 { font-family: var(--f-display); font-weight: 700; font-size: var(--step-1); margin: 0 0 .3rem; }
.domain p { margin: 0; color: var(--mute); font-size: .9375rem; }
.redact {
  position: relative; display: block; height: 1.5rem; background: var(--redact); cursor: help; overflow: hidden;
}
.redact::after {
  content: attr(data-label); position: absolute; inset: 0; display: flex; align-items: center; padding-inline: .6rem;
  font-family: var(--f-mark); font-size: .6875rem; letter-spacing: .12em; color: var(--redact-fg);
  opacity: 0; transform: translateY(6px); transition: opacity .25s, transform .25s;
}
.redact:hover::after, .redact:focus-visible::after { opacity: 1; transform: none; }
.redact + .redact { margin-top: .45rem; width: 72%; }
@media (max-width: 820px) { .domain { grid-template-columns: 1fr; } .redact::after { opacity: 1; transform: none; } }

/* process sequence */
.steps { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0; counter-reset: s; border-top: 1px solid var(--ink); }
.step { padding: 1.6rem 1.4rem 1.8rem 0; border-right: 1px solid var(--line); counter-increment: s; }
.step + .step { padding-left: 1.4rem; }
.step:last-child { border-right: 0; }
.step::before { content: "STEP " counter(s, decimal-leading-zero); font-family: var(--f-mark); font-size: .75rem; letter-spacing: .14em; color: var(--seal); }
.step h3 { font-family: var(--f-display); font-size: var(--step-1); margin: .7rem 0 .4rem; }
.step p { margin: 0; color: var(--mute); font-size: .9375rem; }
@media (max-width: 900px) {
  .steps { grid-template-columns: 1fr 1fr; }
  .step, .step + .step { padding: 1.4rem 1rem 1.6rem 0; border-right: 0; border-bottom: 1px solid var(--line); }
}
@media (max-width: 520px) { .steps { grid-template-columns: 1fr; } }

/* principle pairs */
.pairs { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 2.4rem; }
.pairs h3 { font-family: var(--f-display); font-size: var(--step-1); margin: 0 0 .5rem; }
.pairs p { margin: 0; color: var(--mute); font-size: .9375rem; }
.pairs .k { font-family: var(--f-mark); font-size: .6875rem; letter-spacing: .14em; color: var(--seal); display: block; margin-bottom: .6rem; }
@media (max-width: 820px) { .pairs { grid-template-columns: 1fr; } }

/* call to action */
.cta { padding-block: clamp(4rem, 11vw, 9rem); }
.cta a.big {
  display: inline-flex; align-items: baseline; gap: .4em; text-decoration: none;
  font-family: var(--f-display); font-weight: 800; font-size: var(--step-4); line-height: 1.1;
  background: linear-gradient(var(--redact), var(--redact)) left bottom / 0 100% no-repeat;
  transition: background-size .55s cubic-bezier(.7, 0, .2, 1), color .55s;
  padding-inline: .1em;
}
.cta a.big:hover, .cta a.big:focus-visible { background-size: 100% 100%; color: var(--redact-fg); }
.cta a.big .arr { font-family: var(--f-mark); font-size: .4em; }
.cta p { color: var(--mute); margin: 1.4rem 0 0; }

/* ---------- inner pages ---------- */
.page-hero { padding-block: clamp(3rem, 8vw, 6rem) clamp(2rem, 5vw, 3.5rem); border-bottom: 1px solid var(--line); }
.page-hero h1 { font-family: var(--f-display); font-weight: 800; font-size: var(--step-4); line-height: 1.15; margin: 1rem 0 1rem; text-wrap: balance; }
.page-hero p { color: var(--mute); margin: 0; max-width: 40em; }
.doc-meta { display: flex; flex-wrap: wrap; gap: .3rem 1.6rem; margin-top: 1.6rem; font-family: var(--f-mark); font-size: .75rem; letter-spacing: .08em; color: var(--mute); }

.doc { display: grid; grid-template-columns: minmax(0, 220px) minmax(0, 1fr); gap: 2rem 3rem; padding-block: clamp(2.5rem, 6vw, 4.5rem) clamp(4rem, 9vw, 7rem); }
.toc { position: sticky; top: 6rem; align-self: start; font-size: .8125rem; }
.toc ol { list-style: none; margin: 0; padding: 0; display: grid; gap: .45rem; }
.toc a { text-decoration: none; color: var(--mute); }
.toc a:hover { color: var(--ink); }
.doc-body { max-width: 44em; min-width: 0; }
.doc-body h2 { font-family: var(--f-display); font-size: var(--step-2); line-height: 1.4; margin: 2.8rem 0 .9rem; padding-top: 1.2rem; border-top: 1px solid var(--line); scroll-margin-top: 6rem; }
.doc-body h2:first-child { margin-top: 0; }
.doc-body h2 .n { font-family: var(--f-mark); font-size: .75rem; letter-spacing: .1em; color: var(--seal); display: block; margin-bottom: .3rem; }
.doc-body p, .doc-body li { font-size: .9688rem; }
.doc-body ul, .doc-body ol { padding-left: 1.3em; }
.doc-body li { margin-bottom: .35em; }
.note { border-left: 2px solid var(--seal); padding: .2rem 0 .2rem 1rem; color: var(--mute); font-size: .875rem; }
@media (max-width: 820px) { .doc { grid-template-columns: 1fr; } .toc { position: static; } }

/* definition table */
.spec { width: 100%; border-collapse: collapse; border-top: 1px solid var(--ink); }
.spec th, .spec td { text-align: left; vertical-align: top; padding: 1.1rem 1rem 1.1rem 0; border-bottom: 1px solid var(--line); font-size: .9688rem; }
.spec th { width: 13rem; font-weight: 500; color: var(--mute); }
.spec .num { font-family: var(--f-mark); font-variant-numeric: tabular-nums; letter-spacing: .04em; }
@media (max-width: 600px) { .spec th, .spec td { display: block; width: auto; padding-right: 0; } .spec th { border-bottom: 0; padding-bottom: 0; } }

/* buttons */
.btn {
  display: inline-flex; align-items: center; gap: .8rem; font: inherit; font-size: .9375rem; text-decoration: none;
  padding: .95rem 1.5rem; border: 1px solid var(--ink); background: var(--ink); color: var(--paper); cursor: pointer;
  transition: background .25s, color .25s;
}
.btn:hover { background: transparent; color: var(--ink); }
.btn[aria-disabled="true"] { background: transparent; color: var(--mute); border-color: var(--line); cursor: not-allowed; }
.btn .arr { font-family: var(--f-mark); }

/* form */
.form { display: grid; gap: 1.4rem; max-width: 40em; }
.field { display: grid; gap: .4rem; }
.field label { font-size: .875rem; }
.field label .req { font-family: var(--f-mark); font-size: .6875rem; color: var(--seal); margin-left: .5rem; letter-spacing: .08em; }
.field input, .field textarea, .field select {
  font: inherit; color: var(--ink); background: transparent; border: 0; border-bottom: 1px solid var(--line);
  padding: .6rem 0; border-radius: 0; width: 100%;
}
.field input:focus, .field textarea:focus, .field select:focus { outline: none; border-bottom-color: var(--ink); }
.field textarea { min-height: 9rem; resize: vertical; }
.check { display: flex; gap: .7rem; align-items: flex-start; font-size: .875rem; }
.check input { margin-top: .4rem; accent-color: var(--ink); }
.form-msg { font-size: .875rem; color: var(--seal); min-height: 1.5em; margin: 0; }

/* ---------- footer ---------- */
.site-footer { padding-block: 3.5rem 2.5rem; font-size: .8125rem; color: var(--mute); }
.foot-grid { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr) minmax(0, 1fr); gap: 2rem 3rem; }
.foot-grid .brand .type { width: 150px; }
.foot-grid ul { list-style: none; padding: 0; margin: 0; display: grid; gap: .4rem; }
.foot-grid a { text-decoration: none; }
.foot-grid a:hover { color: var(--ink); }
.foot-grid address { font-style: normal; line-height: 1.9; }
.num { font-variant-numeric: tabular-nums; }
.foot-bottom { margin-top: 3rem; padding-top: 1.2rem; border-top: 1px solid var(--line); display: flex; flex-wrap: wrap; gap: .5rem 2rem; justify-content: space-between; font-family: var(--f-mark); font-size: .6875rem; letter-spacing: .1em; }
@media (max-width: 820px) { .foot-grid { grid-template-columns: 1fr; } }

/* reveal on scroll — visible at rest, only a slight lift is animated */
.rv { transition: transform .9s cubic-bezier(.2, .7, .2, 1), opacity .9s; }
.rv.pre { transform: translateY(14px); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  html { scroll-behavior: auto; }
  .rv.pre { transform: none; opacity: 1; }
}

/* 3・6・9 — トップの 18 マークの周りを巡る数式（装飾。マークそのものは変えない） */
.hero-mark-wrap { position: relative; justify-self: end; width: min(100%, 420px); container-type: inline-size; }
.hero-mark-wrap .hero-mark { position: relative; z-index: 1; width: 100%; justify-self: auto; }
.orbit { position: absolute; inset: 0; pointer-events: none; z-index: 0; }
.orbit span {
  position: absolute; left: 50%; top: 50%; white-space: nowrap;
  font-family: var(--f-mark); font-size: .66rem; letter-spacing: .1em; color: var(--mute);
  transform: translate(-50%, -50%) rotate(var(--a)) translateY(calc(-1 * var(--r)));
}
.orbit-a { opacity: .62; animation: orbit-cw 150s linear infinite; }
.orbit-b { opacity: .34; animation: orbit-ccw 240s linear infinite; }
.orbit-b span { font-size: .6rem; }
@keyframes orbit-cw { to { transform: rotate(360deg); } }
@keyframes orbit-ccw { to { transform: rotate(-360deg); } }
@media (max-width: 720px) { .hero-mark-wrap { justify-self: start; width: 140px; order: -1; } .orbit { display: none; } }
@media (prefers-reduced-motion: reduce) { .orbit-a, .orbit-b { animation: none; } }

/* 永遠に計算され続ける数式（3・6・9 → 9 への収束） */
.calc {
  position: absolute; left: 0; right: 0; top: -58%; height: 56%; z-index: 2; pointer-events: none;
  display: flex; flex-direction: column; justify-content: flex-end; overflow: hidden;
  font-family: var(--f-mark); font-size: .72rem; line-height: 1.75; letter-spacing: .06em; color: var(--mute);
}
.calc div { white-space: nowrap; overflow: hidden; }
.calc div:nth-last-child(n+4) { opacity: .45; }
.calc div:nth-last-child(n+6) { opacity: .2; }
.calc .k { color: var(--seal); }
.calc .c { display: inline-block; width: .6em; border-bottom: 1px solid var(--mute); vertical-align: -.1em; animation: caret 1s steps(2) infinite; }
@keyframes caret { 50% { opacity: 0; } }
.hero .wrap { padding-top: clamp(3rem, 8vw, 7rem); }
@media (max-width: 720px) {
  /* スマホ: マーク（140px）の右の空きに計算の流れを出す。リングは出さない */
  .calc { left: 152px; right: auto; top: 0; height: 100%; width: calc(100vw - 152px - 2.5rem); font-size: .6rem; line-height: 1.6; letter-spacing: .04em; }
  .calc div { text-overflow: clip; }
}