/* =========================================================
   株式会社AI Japan — Corporate LP
   Palette
     紅 (logo red) : #D7000F
     deep red      : #A8000C
     sumi (text)   : #1A1A1C
     gray          : #6A6A70
     hairline      : #E8E6E4
   ========================================================= */

:root {
  --red: #D7000F;
  --red-deep: #A8000C;
  --ink: #1A1A1C;
  --gray: #6A6A70;
  --line: #E8E6E4;
  --bg: #FFFFFF;
  --font-display: "Shippori Mincho", serif;
  --font-body: "Zen Kaku Gothic New", sans-serif;
  --font-mono: "IBM Plex Mono", monospace;
  --header-h: 72px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.9;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
:focus-visible { outline: 2px solid var(--red); outline-offset: 3px; }

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
}
.container--narrow { max-width: 820px; }

/* ---------- eyebrow (mono bilingual label) ---------- */
.eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--gray);
  margin-bottom: 20px;
}
.eyebrow--red { color: var(--red); }
.eyebrow--white { color: rgba(255,255,255,0.85); }

/* ---------- header ---------- */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 28px;
  z-index: 100;
  background: rgba(255,255,255,0);
  transition: background .3s ease, box-shadow .3s ease;
}
.site-header.is-scrolled {
  background: rgba(255,255,255,0.94);
  backdrop-filter: blur(8px);
  box-shadow: 0 1px 0 var(--line);
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand__logo { width: 36px; height: 36px; }
.brand__name {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 17px;
  letter-spacing: 0.04em;
  transition: color .3s ease;
}
/* ヒーロー(紅)に重なる間は白、スクロール後は墨色 */
.site-header:not(.is-scrolled):not(.menu-open) .brand__name { color: #fff; }
.nav { display: flex; align-items: center; gap: 32px; font-size: 14px; font-weight: 500; }
.nav a { position: relative; padding: 6px 0; }
.nav a:not(.nav__cta)::after {
  content: "";
  position: absolute;
  left: 0; bottom: 0;
  width: 100%; height: 1px;
  background: var(--red);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform .25s ease;
}
.nav a:not(.nav__cta):hover::after { transform: scaleX(1); transform-origin: left; }
.nav__cta {
  border: 1px solid var(--red);
  color: var(--red);
  padding: 8px 20px !important;
  transition: background .2s ease, color .2s ease;
}
.nav__cta:hover { background: var(--red); color: #fff; }

.nav-toggle { display: none; }

/* ---------- hero : 紅白の縦割り ---------- */
.hero {
  display: grid;
  grid-template-columns: 42% 58%;
  min-height: 100vh;
  min-height: 100svh;
}

.hero__red {
  background: var(--red);
  color: #fff;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.hero__tagline {
  writing-mode: vertical-rl;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(28px, 3.4vw, 44px);
  letter-spacing: 0.32em;
  line-height: 1.45;
  transform: translateY(1.9em);
  z-index: 2;
}
.hero__tagline-indent {
  display: inline-block;
  transform: translateY(3.1em);
}
.hero__tagline-lift {
  display: inline-block;
  transform: translateY(-0.8em);
}
.hero__mark {
  position: absolute;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 56vh;
  line-height: 1;
  color: rgba(255,255,255,0.08);
  bottom: -10vh;
  left: -4vw;
  user-select: none;
  pointer-events: none;
}
.hero__mark--red {
  color: rgba(215,0,15,0.06);
  left: auto;
  right: -3vw;
  bottom: -12vh;
}

.hero__white {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: calc(var(--header-h) + 24px) 8vw 64px 7vw;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
}
.hero__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(54px, 7.4vw, 96px);
  color: transparent;
  background: linear-gradient(180deg, rgba(26,26,28,0.58) 0%, rgba(26,26,28,0.74) 46%, rgba(26,26,28,0.96) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  line-height: 1.12;
  letter-spacing: 0.02em;
  margin-bottom: 28px;
}
.hero__lead {
  max-width: 34em;
  color: var(--gray);
  font-size: 15px;
  margin-bottom: 40px;
  position: relative;
  z-index: 2;
}
.hero__actions { display: flex; gap: 16px; flex-wrap: wrap; position: relative; z-index: 2; }

/* ---------- buttons ---------- */
.btn {
  display: inline-block;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.08em;
  padding: 14px 36px;
  transition: background .2s ease, color .2s ease, border-color .2s ease;
}
.btn--primary { background: var(--red); color: #fff; }
.btn--primary:hover { background: var(--red-deep); }
.btn--ghost { border: 1px solid var(--ink); color: var(--ink); }
.btn--ghost:hover { border-color: var(--red); color: var(--red); }
.btn--white { background: #fff; color: var(--red); }
.btn--white:hover { background: rgba(255,255,255,0.88); }

/* ---------- sections ---------- */
.section { padding: 120px 0; }
.section__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(26px, 3vw, 36px);
  letter-spacing: 0.08em;
  margin-bottom: 56px;
  position: relative;
  padding-left: 22px;
}
/* 縦の紅ライン = ロゴの「継ぎ目」モチーフ */
.section__title::before {
  content: "";
  position: absolute;
  left: 0; top: 0.18em; bottom: 0.18em;
  width: 3px;
  background: var(--red);
}

/* ---------- mission ---------- */
.mission {
  border-bottom: 1px solid var(--line);
  position: relative;
  overflow: hidden;
}
/* ヒーローの「A」「J」と対をなす透かしの「M」 */
.mission__mark {
  position: absolute;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 46vh;
  line-height: 1;
  color: rgba(215,0,15,0.05);
  top: -8vh;
  right: -2vw;
  user-select: none;
  pointer-events: none;
}
.mission__grid {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
  gap: 56px;
  align-items: start;
}
.mission__statement {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(30px, 4.2vw, 50px);
  line-height: 1.6;
  letter-spacing: 0.06em;
}
.mission__statement em {
  font-style: normal;
  color: var(--red);
}
.mission__body {
  max-width: 44em;
  color: var(--gray);
  display: grid;
  gap: 1.2em;
  padding-top: 0.6em;
}
.mission__principles {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
  margin-top: 88px;
}
.mission__principles li {
  border-top: 1px solid var(--line);
  padding-top: 24px;
}
.mission__principle-index {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--red);
  margin-bottom: 14px;
}
.mission__principles h3 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 20px;
  letter-spacing: 0.1em;
  margin-bottom: 10px;
}
.mission__principles li > p:last-child {
  color: var(--gray);
  font-size: 14px;
}

/* ---------- products ---------- */
.products { background: #FAFAF9; border-bottom: 1px solid var(--line); }
.prod-list { display: grid; gap: 72px; }
.prod-item {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: center;
}
.prod-item--rev .prod-item__visual { order: 2; }
.prod-item--rev .prod-item__info { order: 1; }

/* ブラウザ風モック(画像なしでCSSのみ) */
.prod-item__visual {
  border: 1px solid var(--line);
  background: #fff;
  box-shadow: 0 16px 40px rgba(26,26,28,0.08);
}
.mock-bar {
  display: flex;
  gap: 6px;
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
}
.mock-bar span {
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--line);
}
.mock-body {
  padding: 48px 32px 52px;
  text-align: center;
}
.prod-item__visual--01 .mock-body {
  background: linear-gradient(135deg, rgba(215,0,15,0.04), rgba(215,0,15,0.10));
}
.prod-item__visual--02 .mock-body {
  background: linear-gradient(135deg, rgba(26,26,28,0.03), rgba(215,0,15,0.07));
}
.prod-item__visual--03 .mock-body {
  background: linear-gradient(135deg, rgba(215,0,15,0.08), rgba(26,26,28,0.03));
}
.mock-num {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 64px;
  line-height: 1.1;
  color: var(--red);
}
.mock-num small { font-size: 0.45em; font-weight: 600; }
.mock-label {
  font-size: 12.5px;
  letter-spacing: 0.18em;
  color: var(--gray);
  margin-top: 6px;
}

.prod-item__index {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--red);
  margin-bottom: 14px;
}
.prod-item__info h3 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 28px;
  letter-spacing: 0.06em;
  margin-bottom: 14px;
  display: flex;
  align-items: baseline;
  gap: 14px;
  flex-wrap: wrap;
}
.prod-item__sub {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--gray);
  font-weight: 400;
}
.prod-item__desc { color: var(--gray); font-size: 14.5px; margin-bottom: 22px; }
.prod-item__tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.prod-item__tags li {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--red);
  border: 1px solid rgba(215,0,15,0.35);
  padding: 4px 12px;
}

/* ---------- company ---------- */
.company-table { border-top: 1px solid var(--line); }
.company-table > div {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 24px;
  padding: 22px 8px;
  border-bottom: 1px solid var(--line);
}
.company-table dt {
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.06em;
}
.company-table dd { color: var(--gray); font-size: 14.5px; }

/* ---------- contact ---------- */
.contact {
  background: var(--red);
  color: #fff;
  text-align: center;
}
.contact__inner { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
.contact h2 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(26px, 3.4vw, 40px);
  letter-spacing: 0.08em;
  margin-bottom: 24px;
  white-space: nowrap;
}
.contact__lead {
  color: rgba(255,255,255,0.88);
  font-size: 15px;
  margin-bottom: 40px;
}
.contact__note {
  margin-top: 20px;
  font-size: 12px;
  color: rgba(255,255,255,0.7);
}

/* ---------- footer ---------- */
.site-footer { padding: 36px 0; }
.site-footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--gray);
}
.site-footer__logo { width: 28px; height: 28px; }

/* ---------- reveal animation ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .7s ease, transform .7s ease;
}
.reveal.is-visible { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .mission__grid { grid-template-columns: 1fr; gap: 32px; }
  .mission__statement br { display: none; }
  .mission__body { padding-top: 0; }
  .mission__principles { grid-template-columns: 1fr; gap: 28px; margin-top: 64px; }
  .mission__mark { font-size: 32vh; top: auto; bottom: -6vh; }

  .prod-item { grid-template-columns: 1fr; gap: 24px; }
  .prod-item--rev .prod-item__visual { order: 1; }
  .prod-item--rev .prod-item__info { order: 2; }
  .prod-list { gap: 56px; }
  .mock-num { font-size: 48px; }
}

@media (max-width: 760px) {
  .section { padding: 80px 0; }
  /* hero stacks: red band on top */
  .hero { grid-template-columns: 1fr; min-height: auto; }
  .hero__red { min-height: 38vh; padding: calc(var(--header-h) + 16px) 24px 32px; }
  .hero__tagline { font-size: 26px; }
  .hero__mark { font-size: 40vh; }
  .hero__white { padding: 56px 24px 64px; }

  .brand__name { font-size: 15px; }

  /* mobile nav */
  .nav {
    position: fixed;
    inset: var(--header-h) 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: #fff;
    border-bottom: 1px solid var(--line);
    padding: 8px 0 16px;
    display: none;
  }
  .nav.is-open { display: flex; }
  .nav a { padding: 14px 28px; }
  .nav__cta { margin: 12px 28px 0; text-align: center; }

  .nav-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 6px;
    width: 40px; height: 40px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
  }
  .nav-toggle span {
    display: block;
    height: 2px;
    background: var(--ink);
    transition: transform .25s ease;
  }
  .site-header:not(.is-scrolled) .nav-toggle span { background: #fff; }
  .site-header.menu-open .nav-toggle span { background: var(--ink); }
  .nav-toggle[aria-expanded="true"] span:first-child { transform: translateY(4px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:last-child { transform: translateY(-4px) rotate(-45deg); }

  .company-table > div { grid-template-columns: 1fr; gap: 6px; }
  .contact h2 { white-space: normal; }
}