/* =========================================================
   Grid Systems — Tribute to Josef Müller-Brockmann
   すべての寸法は 8px の基本単位の倍数で構成される。
   ========================================================= */

:root {
  /* --- 基本単位 / Baseline unit --- */
  --unit: 8px;          /* すべての寸法の最小単位 */
  --baseline: 28px;     /* 本文の垂直リズム */

  /* --- グリッド --- */
  --content: 1180px;    /* コンテンツ幅 */
  --cols: 12;           /* カラム数 */
  --gutter: 24px;       /* ガター = unit * 3 */
  --margin: 40px;       /* 外周マージン = unit * 5 */

  /* --- 色: スイス・スタイルの限定パレット --- */
  --ink: #111111;
  --paper: #f4f2ec;
  --red: #e2231a;       /* ミューラー=ブロックマンの赤 */
  --grey: #8a8780;
  --line: rgba(17, 17, 17, 0.14);

  /* --- オーバーレイ --- */
  --ov-col: rgba(226, 35, 26, 0.10);
  --ov-line: rgba(226, 35, 26, 0.55);
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "Inter", "Noto Sans JP", "Helvetica Neue", Arial, sans-serif;
  font-size: 18px;
  line-height: var(--baseline);
  font-feature-settings: "palt" 1;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

p { margin: 0 0 var(--baseline); }
em { font-style: normal; color: var(--red); }
code {
  font-family: "SF Mono", "Menlo", monospace;
  font-size: 0.82em;
  background: rgba(17,17,17,0.06);
  padding: 0.1em 0.4em;
  border-radius: 2px;
}

/* =========================================================
   THE GRID  — 12カラムのモジュラーグリッド
   ========================================================= */
.grid {
  display: grid;
  grid-template-columns: repeat(var(--cols), 1fr);
  column-gap: var(--gutter);
  max-width: calc(var(--content) + var(--margin) * 2);
  margin-inline: auto;
  padding-inline: var(--margin);
}

/* =========================================================
   GRID OVERLAY  — 可視化トグル
   ========================================================= */
.grid-overlay {
  position: fixed;
  inset: 0;
  z-index: 80;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.25s ease;
}
.grid-overlay.is-on { opacity: 1; }

.grid-overlay__inner {
  max-width: calc(var(--content) + var(--margin) * 2);
  height: 100%;
  margin-inline: auto;
  padding-inline: var(--margin);
}
.grid-overlay__columns {
  display: grid;
  grid-template-columns: repeat(var(--cols), 1fr);
  column-gap: var(--gutter);
  height: 100%;
  opacity: 0;
  transition: opacity 0.2s ease;
}
.grid-overlay.show-cols .grid-overlay__columns { opacity: 1; }
.grid-overlay__columns span {
  background: var(--ov-col);
  border-left: 1px solid var(--ov-line);
  border-right: 1px solid var(--ov-line);
}

.grid-overlay__baseline {
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    to bottom,
    var(--ov-line) 0,
    var(--ov-line) 1px,
    transparent 1px,
    transparent var(--baseline)
  );
  opacity: 0;
  transition: opacity 0.2s ease;
}
.grid-overlay.show-base .grid-overlay__baseline { opacity: 0.5; }

/* =========================================================
   CONTROL
   ========================================================= */
.control {
  position: fixed;
  right: var(--margin);
  bottom: var(--margin);
  z-index: 100;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: var(--unit);
}
.control__btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: var(--ink);
  color: var(--paper);
  border: none;
  padding: 12px 18px;
  font-family: inherit;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.02em;
  cursor: pointer;
  border-radius: 2px;
  transition: background 0.2s ease;
}
.control__btn[aria-pressed="true"] { background: var(--red); }
.control__btn:hover { background: var(--red); }
.control__key {
  display: inline-grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border: 1px solid currentColor;
  border-radius: 2px;
  font-size: 12px;
  font-weight: 700;
}
.control__opts[hidden] { display: none; }
.control__opts {
  display: flex;
  gap: 14px;
  background: var(--ink);
  color: var(--paper);
  padding: 10px 14px;
  border-radius: 2px;
  font-size: 13px;
}
.control__opt { display: inline-flex; align-items: center; gap: 6px; cursor: pointer; }
.control__opt input { accent-color: var(--red); }

/* =========================================================
   MASTHEAD
   ========================================================= */
.masthead {
  padding-block: calc(var(--baseline) * 3) calc(var(--baseline) * 2);
  border-bottom: 2px solid var(--ink);
}
.masthead__meta {
  grid-column: 1 / -1;
  display: flex;
  gap: var(--unit);
  margin-bottom: calc(var(--baseline) * 2);
}
.tag {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--paper);
  background: var(--red);
  padding: 4px 10px;
  border-radius: 2px;
}
.tag--muted { background: transparent; color: var(--grey); border: 1px solid var(--line); }

.masthead__title {
  grid-column: 1 / 9;
  margin: 0;
  font-size: clamp(72px, 14vw, 184px);
  line-height: 0.86;
  font-weight: 900;
  letter-spacing: -0.03em;
}
.masthead__sub {
  grid-column: 9 / -1;
  align-self: end;
  margin: 0;
  font-size: 20px;
  font-weight: 700;
  color: var(--red);
  writing-mode: vertical-rl;
  justify-self: end;
}
.masthead__lede {
  grid-column: 1 / 8;
  margin-top: calc(var(--baseline) * 2);
  font-size: 20px;
  line-height: var(--baseline);
}
.masthead__index {
  grid-column: 9 / -1;
  margin: calc(var(--baseline) * 2) 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}
.masthead__index li {
  display: flex;
  gap: 14px;
  padding: 6px 0;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
  font-weight: 500;
}
.masthead__index span { color: var(--red); font-weight: 700; }

/* =========================================================
   SECTION  — 共通レイアウト
   ========================================================= */
.section {
  padding-block: calc(var(--baseline) * 3);
  border-bottom: 1px solid var(--line);
}
.section__num {
  grid-column: 1 / 2;
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: var(--red);
}
.section__title {
  grid-column: 2 / 6;
  margin: 0;
  font-size: clamp(40px, 6vw, 72px);
  line-height: 0.92;
  font-weight: 900;
  letter-spacing: -0.02em;
}
.section__body {
  grid-column: 7 / -1;
}
.lead {
  font-size: 22px;
  line-height: calc(var(--baseline) + 4px);
  font-weight: 500;
}

/* --- 01 module demo --- */
.demo { margin-top: calc(var(--baseline) * 2); row-gap: var(--gutter); }
.module {
  margin: 0;
  padding: var(--gutter);
  border: 1px solid var(--ink);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: calc(var(--baseline) * 6);
}
.module p { margin: 0; font-size: 15px; line-height: 1.5; }
.module__span {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--red);
  margin-bottom: var(--baseline);
}
.module--a { grid-column: 1 / 7; background: var(--ink); color: var(--paper); }
.module--a .module__span { color: var(--paper); }
.module--b { grid-column: 7 / 10; }
.module--c { grid-column: 10 / 13; }
.module--d { grid-column: 1 / 5; background: var(--red); color: var(--paper); border-color: var(--red); }
.module--d .module__span { color: var(--paper); }
.module--e { grid-column: 5 / 9; }
.module--f { grid-column: 9 / 13; }

/* --- 02 rhythm --- */
.rhythm { grid-column: 1 / 8; }
.rhythm__h {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--red);
  margin-bottom: 4px;
}

/* --- 03 ratios --- */
.ratios { margin-top: calc(var(--baseline) * 2); }
.ratio {
  grid-column: span 3;
  border-top: 2px solid var(--ink);
  padding-top: var(--unit);
}
.ratio__val {
  margin: 0;
  font-size: clamp(48px, 6vw, 80px);
  font-weight: 900;
  line-height: 1;
  letter-spacing: -0.03em;
}
.ratio__val span { font-size: 0.3em; font-weight: 500; color: var(--grey); margin-left: 2px; }
.ratio__cap {
  margin: var(--unit) 0 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--ink);
}

/* --- 04 type scale --- */
.scale { margin-top: calc(var(--baseline) * 2); row-gap: 0; }
.scale__row {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: 120px 1fr;
  align-items: baseline;
  gap: var(--gutter);
  padding-block: var(--baseline);
  border-top: 1px solid var(--line);
}
.scale__meta {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 12px;
  color: var(--grey);
  letter-spacing: 0.04em;
}
.scale__sample { margin: 0; }

/* --- 05 invert --- */
.section--invert {
  background: var(--ink);
  color: var(--paper);
  border-bottom: none;
}
.section--invert .section__title { color: var(--paper); }
.section--invert code { background: rgba(244,242,236,0.12); color: var(--paper); }
.pull {
  grid-column: 7 / -1;
  margin: calc(var(--baseline) * 2) 0 0;
}
.pull p {
  margin: 0;
  font-size: clamp(36px, 5vw, 60px);
  line-height: 1.05;
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--red);
}

/* =========================================================
   COLOPHON
   ========================================================= */
.colophon {
  background: var(--ink);
  color: var(--paper);
  padding-block: calc(var(--baseline) * 2);
}
.colophon__brand {
  grid-column: 1 / 4;
  margin: 0;
  font-size: 22px;
  font-weight: 900;
  letter-spacing: -0.01em;
}
.colophon__txt { grid-column: 5 / 8; margin: 0; font-size: 14px; line-height: 1.6; color: #c9c6bf; }
.colophon__spec {
  grid-column: 9 / -1;
  margin: 0;
  font-family: "SF Mono", Menlo, monospace;
  font-size: 12px;
  color: var(--grey);
  text-align: right;
}
.colophon__hint {
  grid-column: 1 / -1;
  margin: var(--baseline) 0 0;
  padding-top: var(--unit);
  border-top: 1px solid rgba(244,242,236,0.15);
  font-size: 13px;
  color: var(--grey);
}
kbd {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 11px;
  border: 1px solid rgba(244,242,236,0.4);
  border-radius: 2px;
  padding: 1px 6px;
}

/* =========================================================
   RESPONSIVE  — グリッドは崩さず、再構成する
   ========================================================= */
@media (max-width: 900px) {
  :root { --margin: 24px; --cols: 6; }
  body { font-size: 16px; }
  .masthead__title { grid-column: 1 / -1; }
  .masthead__sub { grid-column: 1 / -1; writing-mode: horizontal-tb; justify-self: start; margin-top: var(--unit); }
  .masthead__lede,
  .masthead__index { grid-column: 1 / -1; }
  .section__num { grid-column: 1 / -1; }
  .section__title { grid-column: 1 / -1; margin-bottom: var(--baseline); }
  .section__body { grid-column: 1 / -1; }
  .module, .ratio { grid-column: 1 / -1 !important; }
  .rhythm { grid-column: 1 / -1; }
  .pull { grid-column: 1 / -1; }
  .scale__row { grid-template-columns: 80px 1fr; }
  .colophon__brand, .colophon__txt, .colophon__spec { grid-column: 1 / -1; text-align: left; margin-bottom: var(--unit); }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}