/* =========================================================
   CAFORA Brand Book — Stylesheet
   Minimal monochrome (white × black × gray)
   ========================================================= */

/* ---------- Design tokens ---------- */
:root {
  /* Palette */
  --bg:            #ffffff;
  --bg-soft:       #f6f5f3;
  --bg-inverse:    #0a0a0a;
  --ink:           #0a0a0a;
  --ink-2:         #2a2a2a;
  --ink-3:         #6b6b6b;
  --ink-4:         #9a9a9a;
  --line:          #e6e4e0;
  --line-strong:   #c9c7c2;
  --inverse-ink:   #ffffff;
  --inverse-ink-2: #c8c6c2;
  --inverse-line:  #2a2a2a;

  /* Typography */
  --font-en: 'Inter', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  --font-jp: 'Noto Sans JP', 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Yu Gothic', sans-serif;

  /* Layout */
  --nav-w:         288px;
  --content-max:   720px;
  --section-px:    clamp(24px, 6vw, 96px);
  --section-py:    clamp(96px, 14vh, 168px);

  /* Motion */
  --ease-out: cubic-bezier(0.2, 0.7, 0.2, 1);
}

/* ---------- Base ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-jp);
  font-weight: 400;
  font-size: 16px;
  line-height: 1.9;
  letter-spacing: 0.02em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, p, ul, ol, blockquote, figure { margin: 0; padding: 0; }
ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; }

::selection { background: var(--ink); color: var(--bg); }

/* Skip link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 16px;
  background: var(--ink);
  color: var(--bg);
  padding: 8px 12px;
  font-family: var(--font-en);
  font-size: 12px;
  letter-spacing: 0.1em;
  z-index: 1000;
}
.skip-link:focus { top: 16px; }

/* ---------- Side navigation ---------- */
.sidenav {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--nav-w);
  height: 100vh;
  background: var(--bg);
  border-right: 1px solid var(--line);
  z-index: 50;
  overflow-y: auto;
  overscroll-behavior: contain;
}

.sidenav__inner {
  min-height: 100%;
  display: flex;
  flex-direction: column;
  padding: 40px 32px 32px;
}

.sidenav__brand {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 48px;
}
.sidenav__brand-mark {
  font-family: var(--font-en);
  font-weight: 500;
  font-size: 20px;
  letter-spacing: 0.32em;
  color: var(--ink);
}
.sidenav__brand-sub {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--ink-3);
  text-transform: uppercase;
}

.sidenav__nav { flex: 1; }

.sidenav__group + .sidenav__group {
  margin-top: 32px;
}

.sidenav__group-title {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin-bottom: 12px;
}

.sidenav__list {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.sidenav__list a {
  display: grid;
  grid-template-columns: 30px 1fr;
  align-items: baseline;
  gap: 12px;
  padding: 8px 0;
  font-family: var(--font-en);
  font-size: 12.5px;
  letter-spacing: 0.04em;
  color: var(--ink-3);
  transition: color 0.25s var(--ease-out);
  position: relative;
}
.sidenav__list a .num {
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--ink-4);
  transition: color 0.25s var(--ease-out);
}
.sidenav__list a .label {
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
  transition: border-color 0.25s var(--ease-out), color 0.25s var(--ease-out);
}
.sidenav__list a:hover,
.sidenav__list a:focus-visible {
  color: var(--ink);
  outline: none;
}
.sidenav__list a:hover .num,
.sidenav__list a:focus-visible .num { color: var(--ink-2); }

.sidenav__list a.is-current {
  color: var(--ink);
}
.sidenav__list a.is-current .num { color: var(--ink); }
.sidenav__list a.is-current .label {
  border-bottom-color: var(--ink);
}

.sidenav__footer {
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-family: var(--font-en);
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--ink-4);
  text-transform: uppercase;
}

/* ---------- Hamburger toggle (mobile) ---------- */
.menu-toggle {
  position: fixed;
  top: 18px;
  right: 18px;
  width: 44px;
  height: 44px;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 999px;
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  z-index: 100;
  cursor: pointer;
  padding: 0;
}
.menu-toggle span {
  display: block;
  width: 18px;
  height: 1px;
  background: var(--ink);
  transition: transform 0.3s var(--ease-out), opacity 0.2s var(--ease-out);
}
.menu-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}
.menu-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.menu-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

.backdrop {
  position: fixed;
  inset: 0;
  background: rgba(10, 10, 10, 0.4);
  z-index: 40;
  opacity: 0;
  transition: opacity 0.3s var(--ease-out);
}
.backdrop.is-visible { opacity: 1; }

/* ---------- Main / sections ---------- */
.main {
  margin-left: var(--nav-w);
}

.section {
  position: relative;
  padding: var(--section-py) var(--section-px);
  border-bottom: 1px solid var(--line);
}
.section:last-of-type { border-bottom: none; }

.section--soft { background: var(--bg-soft); }

.section--part {
  padding: clamp(72px, 11vh, 128px) var(--section-px) clamp(40px, 6vh, 64px);
  border-bottom: none;
}

.main > .section--part:not(:first-child) {
  border-top: 1px solid var(--line-strong);
}

.section-part__title {
  font-family: var(--font-en);
  font-size: clamp(36px, 5.5vw, 64px);
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink);
  margin: 0;
  line-height: 1.15;
}

.section-part__title::after {
  content: '';
  display: block;
  width: 48px;
  height: 1px;
  background: var(--ink);
  margin-top: 24px;
}

.section--inverse {
  background: var(--bg-inverse);
  color: var(--inverse-ink);
  border-bottom: none;
}

.section__inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

.section__eyebrow {
  font-family: var(--font-en);
  font-size: 11.5px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin-bottom: 32px;
  display: flex;
  align-items: center;
  gap: 16px;
}
.section__eyebrow .eyebrow-num {
  font-weight: 500;
  color: var(--ink);
  border: 1px solid var(--line-strong);
  padding: 4px 8px;
  letter-spacing: 0.18em;
  font-size: 10.5px;
}
.section__eyebrow--inverse { color: var(--inverse-ink-2); }
.section__eyebrow--inverse .eyebrow-num {
  color: var(--inverse-ink);
  border-color: var(--inverse-line);
}

.section__title {
  font-family: var(--font-jp);
  font-weight: 500;
  font-size: clamp(28px, 4.4vw, 44px);
  line-height: 1.55;
  letter-spacing: 0.02em;
  color: var(--ink);
  margin-bottom: 48px;
}
.section__title--large {
  font-size: clamp(32px, 5vw, 52px);
  line-height: 1.5;
  font-weight: 500;
}
.section__body { font-size: 16px; }

/* ---------- Hero (section 01) ---------- */
.section--hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: calc(var(--section-py) + 32px);
}
.hero__headline {
  font-family: var(--font-jp);
  font-weight: 500;
  font-size: clamp(36px, 6.4vw, 72px);
  line-height: 1.35;
  letter-spacing: 0.04em;
  color: var(--ink);
  margin-bottom: 56px;
}
.hero__line {
  display: block;
  overflow: hidden;
}
.hero__body {
  max-width: 520px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  color: var(--ink-2);
  font-size: 15.5px;
  line-height: 2;
}
.hero__body p { margin: 0; }

/* ---------- Prose ---------- */
.prose {
  display: flex;
  flex-direction: column;
  gap: 20px;
  font-size: 16px;
  line-height: 2;
  color: var(--ink-2);
  max-width: 640px;
}
.prose p { margin: 0; }
.prose__lead {
  font-size: 18px;
  color: var(--ink);
  font-weight: 500;
}
.prose__verses {
  display: flex;
  flex-direction: column;
  gap: 6px;
  color: var(--ink);
}
.prose__verses span { display: block; }

.prose__emphasis {
  display: flex;
  flex-direction: column;
  gap: 8px;
  color: var(--ink);
  font-weight: 500;
  border-left: 1px solid var(--line-strong);
  padding-left: 20px;
  margin-top: 8px;
}

.prose__highlight {
  font-weight: 500;
  color: var(--ink);
  letter-spacing: 0.05em;
}

.prose__quote {
  font-family: var(--font-jp);
  font-weight: 500;
  font-size: 20px;
  line-height: 1.8;
  color: var(--ink);
  padding: 24px 0 24px 24px;
  border-left: 2px solid var(--ink);
  margin: 8px 0;
}

.prose__list {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding-left: 4px;
}
.prose__list li {
  position: relative;
  padding-left: 24px;
  color: var(--ink);
}
.prose__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: calc(1em - 1px);
  width: 12px;
  height: 1px;
  background: var(--ink);
}

/* ---------- Step list (Mission) ---------- */
.step-list {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  margin: 0 0 48px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.step-list li {
  padding: 28px 20px;
  border-right: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.step-list li:last-child { border-right: none; }
.step-list__num {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--ink-3);
}
.step-list__label {
  font-size: 16px;
  color: var(--ink);
  font-weight: 500;
}

/* ---------- Cards ---------- */
.cards {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.cards--four { grid-template-columns: repeat(2, 1fr); }
.cards--two  { grid-template-columns: repeat(2, 1fr); }

.card {
  background: var(--bg);
  padding: 36px 32px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.section--soft .card { background: var(--bg-soft); }

.card__eyebrow {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--ink-3);
}
.card__title-en {
  font-family: var(--font-en);
  font-weight: 500;
  font-size: 20px;
  letter-spacing: 0.04em;
  color: var(--ink);
  margin: 0;
}
.card__title-jp {
  font-size: 15px;
  font-weight: 500;
  color: var(--ink-2);
  letter-spacing: 0.05em;
}
.card__body {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 14.5px;
  color: var(--ink-3);
  line-height: 1.95;
}
.card__body p { margin: 0; }

.cards--minimal { background: var(--line); }
.card--minimal {
  padding: 40px 32px;
  gap: 12px;
}
.card--minimal .card__title-en {
  font-size: 24px;
  letter-spacing: 0.08em;
}
.card__body-line {
  font-size: 14.5px;
  color: var(--ink-3);
  margin-top: 8px;
}

/* ---------- Ordered steps (Form Follows Experience) ---------- */
.ordered-steps {
  counter-reset: step;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 24px 0 8px;
  border-top: 1px solid var(--line);
}
.ordered-steps li {
  counter-increment: step;
  position: relative;
  padding-left: 56px;
  color: var(--ink);
  font-size: 16px;
  line-height: 1.8;
}
.ordered-steps li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0;
  font-family: var(--font-en);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--ink-3);
  border: 1px solid var(--line-strong);
  padding: 2px 8px;
}

/* ---------- Hypothesis list (Product Development) ---------- */
.hypothesis-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin: 8px 0 4px;
}
.hypothesis-list li {
  padding: 16px 20px;
  background: var(--bg);
  border-left: 2px solid var(--ink);
  font-size: 15.5px;
  color: var(--ink);
  line-height: 1.8;
}
.section--soft .hypothesis-list li { background: var(--bg); }

/* ---------- Product cards (ON / KAKU) ---------- */
.product-card {
  background: var(--bg);
  padding: 40px 36px;
  display: flex;
  flex-direction: column;
  gap: 28px;
}
.product-card__header {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--line);
}
.product-card__series {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--ink-3);
}
.product-card__name {
  font-family: var(--font-en);
  font-weight: 500;
  font-size: 44px;
  letter-spacing: 0.16em;
  color: var(--ink);
  margin: 0;
}
.product-card__row {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.product-card__label {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--ink-3);
  text-transform: uppercase;
}
.product-card__exp {
  font-size: 18px;
  color: var(--ink);
  font-weight: 500;
}
.product-card__list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.product-card__list li {
  position: relative;
  padding-left: 20px;
  color: var(--ink-2);
  font-size: 15px;
  line-height: 1.9;
}
.product-card__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: calc(0.95em);
  width: 10px;
  height: 1px;
  background: var(--ink);
}

/* ---------- Manifesto (inverse) ---------- */
.section--inverse .section__inner { max-width: 760px; }

.manifesto {
  display: flex;
  flex-direction: column;
  gap: 28px;
  font-size: 18px;
  line-height: 2;
  color: var(--inverse-ink);
  letter-spacing: 0.04em;
}
.manifesto p { margin: 0; }
.manifesto__verses {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.manifesto__verses span { display: block; }

.manifesto__break {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.manifesto__break span { display: block; }
.manifesto__strong {
  font-size: 24px;
  font-weight: 500;
  letter-spacing: 0.06em;
}

.manifesto__sign {
  margin-top: 80px;
  padding-top: 40px;
  border-top: 1px solid var(--inverse-line);
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.manifesto__brand {
  font-family: var(--font-en);
  font-weight: 500;
  font-size: 28px;
  letter-spacing: 0.36em;
  color: var(--inverse-ink);
}
.manifesto__tagline {
  font-size: 14px;
  letter-spacing: 0.08em;
  color: var(--inverse-ink-2);
}

/* ---------- Site footer ---------- */
.site-footer {
  background: var(--bg);
  padding: 56px var(--section-px);
  border-top: 1px solid var(--line);
}
.site-footer__inner {
  max-width: var(--content-max);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.site-footer__brand {
  font-family: var(--font-en);
  font-weight: 500;
  font-size: 16px;
  letter-spacing: 0.36em;
  color: var(--ink);
}
.site-footer__meta {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--ink-3);
  text-transform: uppercase;
}
.site-footer__copy {
  font-family: var(--font-en);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--ink-4);
}

/* ---------- Scroll reveal ---------- */
[data-animate] > .section__inner {
  opacity: 0;
  transform: translateY(24px);
  transition:
    opacity 0.9s var(--ease-out),
    transform 0.9s var(--ease-out);
}
[data-animate].is-visible > .section__inner {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  [data-animate] > .section__inner {
    opacity: 1;
    transform: none;
  }
}

/* ---------- Responsive ---------- */
@media (max-width: 1024px) {
  :root {
    --nav-w: 260px;
  }
}

@media (max-width: 860px) {
  .menu-toggle { display: flex; }

  .sidenav {
    transform: translateX(-100%);
    transition: transform 0.35s var(--ease-out);
    width: min(320px, 86vw);
    box-shadow: 0 0 0 rgba(0, 0, 0, 0);
  }
  .sidenav.is-open {
    transform: translateX(0);
    box-shadow: 0 24px 60px rgba(0, 0, 0, 0.12);
  }

  .main { margin-left: 0; }

  .section--hero { min-height: auto; padding-top: 140px; }

  .step-list { grid-template-columns: repeat(2, 1fr); }
  .step-list li:nth-child(2n) { border-right: none; }
  .step-list li:nth-child(-n+2) { border-bottom: 1px solid var(--line); }

  .cards--four { grid-template-columns: 1fr; }
  .cards--two  { grid-template-columns: 1fr; }
}

@media (max-width: 520px) {
  body { font-size: 15px; }

  .hero__headline { font-size: clamp(32px, 9vw, 44px); }
  .section__title { font-size: clamp(24px, 6.4vw, 32px); }

  .product-card { padding: 32px 24px; }
  .product-card__name { font-size: 36px; }

  .manifesto { font-size: 16px; }
  .manifesto__strong { font-size: 20px; }
}