/* ============================================================
   Impress Racing — Shared Stylesheet
   Used by /sf/ and /f4/ sub-sites
   ============================================================ */

:root {
  --ink: #0a0a0a;
  --paper: #f5f4ef;
  --paper-2: #ebe9e2;
  --rouge: #ff1d4c;
  --rouge-deep: #c81038;
  --gold: #c8a96a;
  --line: rgba(10, 10, 10, 0.12);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html {
  scroll-behavior: smooth;
  overflow-x: hidden; /* bodyではなくhtmlに設定することでiOS Safari sticky問題を回避 */
}
body {
  background: var(--paper);
  color: var(--ink);
  font-family: "Noto Sans JP", sans-serif;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }

/* ===== Site Header ===== */
.siteheader {
  height: 64px;
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  background: var(--paper);
  position: -webkit-sticky; /* iOS Safari 旧バージョン対応 */
  position: sticky;
  top: 0;
  z-index: 100; /* GPU合成レイヤーの上に確実に描画 */
  -webkit-transform: translateZ(0);
  transform: translateZ(0); /* iOS Safari で compositor layer を正しく確保 */
}
.siteheader__logo { font-family: "Bebas Neue", sans-serif; letter-spacing: 0.18em; font-size: 18px; }
.siteheader__logo span { color: var(--rouge); }
.siteheader nav ul { display: flex; gap: 28px; list-style: none; font-size: 12px; letter-spacing: 0.14em; }
.siteheader nav a:hover { color: var(--rouge); }
.siteheader nav .current { color: var(--rouge); border-bottom: 1px solid var(--rouge); padding-bottom: 4px; }

/* ===== Series Sub-Header ===== */
.subheader {
  background: var(--ink);
  color: #fff;
  padding: 18px 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.subheader__name {
  font-family: "Anton", sans-serif;
  font-size: 24px;
  letter-spacing: 0.06em;
}
.subheader__name small {
  font-family: "Noto Serif JP", serif;
  font-weight: 700;
  font-size: 12px;
  letter-spacing: 0.18em;
  color: rgba(255,255,255,0.6);
  margin-left: 12px;
}
.subheader nav ul {
  display: flex;
  gap: 24px;
  list-style: none;
  font-family: "Bebas Neue", sans-serif;
  font-size: 12px;
  letter-spacing: 0.22em;
}
.subheader nav a { color: rgba(255,255,255,0.7); transition: color .2s; }
.subheader nav a:hover { color: #fff; }
.subheader nav .current { color: var(--rouge); }

.crumb {
  padding: 18px 32px;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: #777;
  border-bottom: 1px solid var(--line);
}
.crumb span { color: var(--ink); }
.crumb a:hover { color: var(--rouge); }

/* ===== HERO (series top) ===== */
.hero {
  position: relative;
  z-index: 0; /* 明示的なスタッキングコンテキストでsiteheaderより下に固定 */
  height: 78vh;
  min-height: 580px;
  background: #050505;
  color: #fff;
  overflow: hidden;
}
.hero__bg {
  position: absolute; inset: 0;
  background-size: cover;
  background-position: center 30%;
  filter: saturate(1.05) contrast(1.05);
  animation: heroZoom 18s ease-in-out infinite alternate;
}
@keyframes heroZoom {
  from { transform: scale(1.02); }
  to   { transform: scale(1.08); }
}
.hero__scrim {
  position: absolute; inset: 0;
  background:
    linear-gradient(180deg, rgba(0,0,0,0.4) 0%, rgba(0,0,0,0.1) 35%, rgba(0,0,0,0.85) 100%),
    linear-gradient(90deg, rgba(0,0,0,0.6) 0%, transparent 50%);
}
.hero__grain {
  position: absolute; inset: 0;
  background-image: repeating-linear-gradient(0deg, rgba(255,255,255,0.02) 0, rgba(255,255,255,0.02) 1px, transparent 1px, transparent 3px);
  pointer-events: none;
}
.hero__corner {
  position: absolute;
  font-family: "Bebas Neue", sans-serif;
  letter-spacing: 0.25em;
  font-size: 10px;
  color: rgba(255,255,255,0.5);
  z-index: 2;
}
.hero__corner--tl { top: 24px; left: 32px; }
.hero__corner--tr { top: 24px; right: 32px; }
.hero__content {
  position: relative;
  z-index: 2;
  height: 100%;
  display: flex;
  align-items: flex-end;
  padding: 0 32px 64px;
}
.hero__inner {
  width: 100%;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: end;
  gap: 32px;
}
.hero__kicker {
  font-family: "Bebas Neue", sans-serif;
  font-size: 12px;
  letter-spacing: 0.4em;
  color: var(--rouge);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.hero__kicker::before { content: ""; width: 32px; height: 1px; background: var(--rouge); }
.hero__title {
  font-family: "Noto Serif JP", serif;
  font-weight: 900;
  font-size: clamp(40px, 6vw, 80px);
  line-height: 1.0;
  letter-spacing: 0.01em;
}
.hero__title .lg {
  font-family: "Anton", sans-serif;
  display: block;
  font-size: clamp(72px, 11vw, 160px);
  letter-spacing: 0.02em;
  line-height: 0.85;
}
.hero__sub {
  margin-top: 24px;
  font-size: 14px;
  line-height: 1.9;
  color: rgba(255,255,255,0.75);
  max-width: 540px;
}
.hero__meter {
  text-align: right;
  border-left: 1px solid rgba(255,255,255,0.15);
  padding-left: 32px;
}
.hero__meter dt {
  font-family: "Bebas Neue", sans-serif;
  font-size: 10px;
  letter-spacing: 0.3em;
  color: rgba(255,255,255,0.55);
}
.hero__meter dd {
  font-family: "Anton", sans-serif;
  font-size: 56px;
  color: #fff;
  line-height: 1;
  margin: 6px 0 18px;
}
.hero__meter dd small {
  font-size: 14px;
  color: var(--rouge);
  margin-left: 8px;
  letter-spacing: 0.1em;
}

/* ===== Section Heads ===== */
.section {
  padding: 96px 32px 64px;
}
.section--dark { background: var(--ink); color: #fff; }
.section--paper2 { background: var(--paper-2); }

.section__head {
  max-width: 1280px;
  margin: 0 auto 48px;
  border-bottom: 1px solid var(--ink);
  padding-bottom: 18px;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}
.section--dark .section__head { border-bottom-color: rgba(255,255,255,0.18); }
.section__head h2 {
  font-family: "Anton", sans-serif;
  font-size: 56px;
  letter-spacing: 0.04em;
  line-height: 1;
}
.section__head h2 small {
  display: block;
  font-family: "Noto Serif JP", serif;
  font-size: 14px;
  letter-spacing: 0.18em;
  margin-bottom: 8px;
  color: var(--rouge);
}
.section__head .index {
  font-family: "Bebas Neue", sans-serif;
  letter-spacing: 0.2em;
  font-size: 12px;
  color: #777;
}
.section--dark .section__head .index { color: rgba(255,255,255,0.5); }

/* ===== Hub Cards (top of series page) ===== */
.hub__grid {
  max-width: 1280px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.hub__card {
  background: var(--paper);
  padding: 36px 32px 40px;
  position: relative;
  transition: background .35s ease, color .35s ease;
  min-height: 280px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}
.hub__card:hover { background: var(--ink); color: #fff; }
.hub__card:hover .hub__card__num,
.hub__card:hover .hub__card__arrow { color: var(--rouge); }
.hub__card__num {
  font-family: "Anton", sans-serif;
  font-size: 14px;
  letter-spacing: 0.3em;
  color: var(--rouge);
}
.hub__card__title-jp {
  font-family: "Noto Serif JP", serif;
  font-weight: 900;
  font-size: 30px;
  line-height: 1.25;
  letter-spacing: 0.02em;
  margin-top: 18px;
}
.hub__card__title-en {
  margin-top: 10px;
  font-family: "Anton", sans-serif;
  font-size: 13px;
  letter-spacing: 0.24em;
  color: #777;
}
.hub__card:hover .hub__card__title-en { color: rgba(255,255,255,0.55); }
.hub__card__desc {
  margin-top: 16px;
  font-size: 13px;
  line-height: 1.8;
  color: #555;
}
.hub__card:hover .hub__card__desc { color: rgba(255,255,255,0.78); }
.hub__card__arrow {
  margin-top: 24px;
  font-family: "Bebas Neue", sans-serif;
  letter-spacing: 0.2em;
  font-size: 13px;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  transition: gap .25s ease;
}
.hub__card:hover .hub__card__arrow { gap: 18px; color: var(--rouge); }

/* ===== Endnote ===== */
.endnote {
  background: var(--ink);
  color: rgba(255,255,255,0.5);
  padding: 32px;
  text-align: center;
  font-size: 11px;
  letter-spacing: 0.2em;
  font-family: "Bebas Neue", sans-serif;
}
.endnote span { color: var(--rouge); }

/* ===== Back link ===== */
.back {
  background: var(--paper);
  padding: 48px 32px;
  text-align: center;
}
.back a {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-family: "Bebas Neue", sans-serif;
  letter-spacing: 0.25em;
  font-size: 14px;
  padding: 14px 24px;
  border: 1px solid var(--ink);
  transition: background .25s ease, color .25s ease, gap .25s ease;
}
.back a:hover { background: var(--ink); color: var(--paper); gap: 20px; }

/* ===== Note Block ===== */
.note {
  max-width: 1280px;
  margin: 24px auto 0;
  padding: 24px;
  border-left: 3px solid var(--rouge);
  background: #fff;
  font-size: 12px;
  color: #555;
  line-height: 1.9;
}
.note strong {
  font-family: "Bebas Neue", sans-serif;
  letter-spacing: 0.2em;
  color: var(--rouge);
  margin-right: 8px;
}
.note a { color: var(--rouge); text-decoration: underline; }

/* ===== Responsive ===== */
@media (max-width: 980px) {
  .hub__grid { grid-template-columns: 1fr; }
  .hero__inner { grid-template-columns: 1fr; }
  .hero__meter { border-left: 0; padding-left: 0; text-align: left; margin-top: 16px; }
  .siteheader nav { display: none; }
  .subheader { flex-direction: column; gap: 12px; align-items: flex-start; }
  .subheader nav ul { gap: 16px; flex-wrap: wrap; }
  /* SP: ヒーロー上部の装飾テキストを非表示（header との干渉を防ぐ） */
  .hero__corner { display: none; }
}