/* IroIro Kanji: one study-desk column; the cards are the hero, colour does the talking. */
:root {
  --paper: #fbfbf9;
  --ink: #1d2230;
  --muted: #5c6373;
  --line: #e2e3e6;
  --card: #ffffff;
  --c-blue: #2499ea;   /* the deck's blue */
  --c-orange: #da6817; /* the deck's orange */
  --sans: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
  --jp: "Noto Sans JP", "Hiragino Sans", "Yu Gothic", sans-serif;
  --step-0: 1rem; --step-1: 1.15rem; --step-2: 1.5rem;
  --step-3: clamp(1.8rem, 5vw, 3rem); --step-4: clamp(2.3rem, 8vw, 4.6rem);
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #14161c; --ink: #eceef2; --muted: #a3a9b6; --line: #2b2f39; --card: #1c1f27;
    --c-blue: #4cb0f2; --c-orange: #f08a3e; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #14161c; --ink: #eceef2; --muted: #a3a9b6; --line: #2b2f39; --card: #1c1f27;
  --c-blue: #4cb0f2; --c-orange: #f08a3e; color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font-family: var(--sans); font-size: var(--step-0); line-height: 1.6; padding: 0 16px; overflow-x: hidden; }
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; }
.wrap { max-width: 1040px; margin: 0 auto; padding-block: 20px 48px; display: grid; gap: 72px; }
h1, h2, h3 { line-height: 1.08; text-wrap: balance; margin: 0; letter-spacing: -.02em; }
p { margin: 0; max-width: 62ch; }
ul { margin: 0; padding-left: 1.2em; max-width: 62ch; }
li + li { margin-top: 6px; }
.jp, [lang="ja"] { font-family: var(--jp); }
.eyebrow { font-weight: 700; font-size: .78rem; letter-spacing: .12em; text-transform: uppercase; color: var(--muted); }
.blue { color: var(--c-blue); } .orange { color: var(--c-orange); }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 8px; background: var(--ink); color: var(--paper); padding: 8px 12px; border-radius: 8px; z-index: 10; }
:focus-visible { outline: 3px solid var(--c-blue); outline-offset: 2px; }

/* Header */
header.top { display: flex; justify-content: space-between; align-items: center; gap: 12px 16px; flex-wrap: wrap; }
.logo { font-weight: 800; font-size: 1.3rem; letter-spacing: -.02em; text-decoration: none; white-space: nowrap; }
.logo .i1 { color: var(--c-blue); } .logo .i2 { color: var(--c-orange); }
.logo small { font-family: var(--jp); font-weight: 500; font-size: .85rem; color: var(--muted); margin-left: 6px; letter-spacing: 0; }
.lang { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; padding: 3px; gap: 2px; }
.lang a { text-decoration: none; color: var(--muted); border-radius: 999px; padding: 4px 12px; font-size: .9rem; font-weight: 600; }
.lang a[aria-current="page"] { background: var(--ink); color: var(--paper); }
.date-chip { font-size: .85rem; color: var(--muted); border: 1px solid var(--line); border-radius: 999px; padding: 4px 12px; display: inline-block; }

/* Hero */
.hero { display: grid; gap: 40px; align-items: center; }
.hero .jp-title { font-family: var(--jp); font-weight: 700; font-size: clamp(1.3rem, 4vw, 1.8rem); color: var(--muted); letter-spacing: .04em; margin-bottom: 10px; }
.hero h1 { font-size: var(--step-4); font-weight: 800; }
.hero .lede { font-size: var(--step-1); color: var(--muted); margin-top: 18px; }
.cta { margin-top: 26px; display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.btn { display: inline-flex; align-items: center; justify-content: center; text-align: center; font: inherit; font-weight: 700; text-decoration: none; background: var(--ink); color: var(--paper); border: 1.5px solid var(--ink); border-radius: 10px; padding: 12px 18px; cursor: pointer; line-height: 1.3; }
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn[aria-disabled="true"] { opacity: .5; cursor: not-allowed; }
.cta-note { margin-top: 10px; font-size: .9rem; color: var(--muted); }

.fan { position: relative; width: min(340px, 70vw); left: -6%; aspect-ratio: 744 / 1122; justify-self: center; margin: 12px auto 24px; }
.fan img { position: absolute; inset: 0; width: 100%; border-radius: 14px; border: 1px solid var(--line); background: #fff; box-shadow: 0 18px 40px -24px rgba(20, 30, 60, .45); }
.fan .back { transform: translate(12%, 3%) rotate(5deg); }
.fan .front { transform: rotate(-3deg); }
@media (prefers-reduced-motion: no-preference) {
  .fan img { transition: transform .4s ease; }
  .fan:hover .front { transform: rotate(0) translateY(-4px); }
}

/* Sections */
section h2 { font-size: var(--step-3); font-weight: 800; }
.stack { display: grid; gap: 16px; align-content: start; }
.split { display: grid; gap: 32px; align-items: start; }
.split > * { min-width: 0; }
.note { font-size: .9rem; color: var(--muted); }
.pair { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.pair figure, .gallery figure { margin: 0; display: grid; gap: 8px; }
.pair img, .gallery img { border-radius: 12px; border: 1px solid var(--line); background: #fff; }
figcaption { font-size: .85rem; color: var(--muted); }
.story { border-left: 4px solid var(--line); padding: 4px 0 4px 14px; font-size: var(--step-1); }
.story b.k1 { color: var(--c-orange); } .story b.k2 { color: #2f8a4a; }
.gallery { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; max-width: 760px; }

.facts { display: grid; grid-template-columns: 1fr; border-top: 1px solid var(--line); }
.facts div { padding: 18px 16px 0 0; display: grid; gap: 2px; min-width: 0; }
.facts strong { font-size: var(--step-2); font-variant-numeric: tabular-nums; letter-spacing: -.01em; }
.facts span { color: var(--muted); font-size: .95rem; }

.boxes { display: grid; grid-template-columns: 1.3fr 1fr; gap: 12px; align-items: end; }
.boxes img { border-radius: 12px; border: 1px solid var(--line); background: #fff; }

.panel { background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 24px 20px; display: grid; gap: 16px; }
.buy { display: grid; gap: 12px; }
.buy-item { display: grid; gap: 10px; border-top: 1px solid var(--line); padding-top: 14px; }
.buy-item h3 { font-size: 1.1rem; letter-spacing: -.01em; }
.buy-item p { color: var(--muted); font-size: .95rem; }
.buy-item .btn { justify-self: start; }

details { border-top: 1px solid var(--line); padding: 14px 0; }
details:last-child { border-bottom: 1px solid var(--line); }
summary { cursor: pointer; font-weight: 700; }
details p { margin-top: 8px; color: var(--muted); }

footer { border-top: 1px solid var(--line); padding-top: 20px; font-size: .9rem; color: var(--muted); display: flex; justify-content: space-between; gap: 12px 24px; flex-wrap: wrap; }
footer nav { display: flex; gap: 16px; flex-wrap: wrap; }

.prose { max-width: 680px; display: grid; gap: 16px; }
.prose h1 { font-size: var(--step-3); font-weight: 800; }
.prose h2 { font-size: var(--step-2); margin-top: 12px; }

@media (min-width: 640px) {
  .facts { grid-template-columns: repeat(3, 1fr); }
  .buy { grid-template-columns: repeat(3, 1fr); gap: 20px; }
  .buy-item { border-top: 0; padding-top: 0; align-content: start; }
  .panel { padding: 32px; }
}
@media (min-width: 860px) {
  body { padding: 0 24px; }
  .wrap { gap: 96px; padding-block: 32px 64px; }
  .hero { grid-template-columns: 1.1fr .9fr; gap: 48px; }
  .split { grid-template-columns: 1fr 1fr; gap: 48px; }
}
.wrap.inner { padding: 0; }
.cta.flush { margin-top: 0; }