/* ==========================================================================
   TARO. 本棚サイト — スタイル定義
   依存ライブラリなし。全てこのファイル内で完結します。
   ========================================================================== */

:root {
  /* カラー */
  --color-navy-deep: #0B1220;
  --color-slate-black: #172033;
  --color-slate-light: #F3F6FA;
  --color-white: #FFFFFF;
  --color-cobalt: #2563EB;
  --color-cyan: #22D3EE;
  --color-orange: #FDBA74;

  --color-text-body: var(--color-slate-black);
  --color-text-muted: #4B5568;
  --color-border: #E2E8F0;

  /* タイポグラフィ */
  --font-sans:
    "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP",
    "Yu Gothic UI", "Meiryo", -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;

  /* レイアウト */
  --content-max-width: 1080px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-soft: 0 8px 24px rgba(11, 18, 32, 0.08);

  /* トランジション（reduced-motion指定時は下部で無効化） */
  --transition-fast: 160ms ease;
}

/* ---- モーション配慮（最優先で定義） ---- */
@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;
  }
}

/* ---- リセット・ベース ---- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background-color: var(--color-white);
  color: var(--color-text-body);
  font-family: var(--font-sans);
  font-weight: 700;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  display: block;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

a {
  color: var(--color-cobalt);
  text-decoration-thickness: 2px;
  text-underline-offset: 2px;
}

h1,
h2,
h3 {
  font-weight: 800;
  line-height: 1.4;
  margin: 0;
}

p {
  margin: 0;
}

/* ---- アクセシビリティ共通部品 ---- */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: -48px;
  left: 12px;
  z-index: 100;
  background: var(--color-navy-deep);
  color: var(--color-white);
  padding: 12px 20px;
  border-radius: var(--radius-md);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 12px;
}

:focus-visible {
  outline: 3px solid var(--color-cyan);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---- レイアウト共通 ---- */
.section-inner,
.site-header__inner,
.hero__inner,
.site-footer__inner {
  max-width: var(--content-max-width);
  margin-inline: auto;
  padding-inline: 20px;
}

.section-heading {
  font-size: clamp(1.375rem, 1.1rem + 1.2vw, 1.875rem);
  color: var(--color-navy-deep);
  margin-bottom: 24px;
}

/* ---- ヘッダー ---- */
.site-header {
  background-color: var(--color-navy-deep);
}

.site-header__inner {
  padding-block: 20px;
}

.brand {
  color: var(--color-white);
  font-size: clamp(1.125rem, 1rem + 0.5vw, 1.375rem);
  font-weight: 800;
  letter-spacing: 0.03em;
  margin: 0;
}

.brand--small {
  font-size: 1rem;
}

/* ---- ヒーロー ---- */
.hero {
  background:
    radial-gradient(circle at 18% 20%, rgba(34, 211, 238, 0.16), transparent 45%),
    radial-gradient(circle at 82% 0%, rgba(37, 99, 235, 0.24), transparent 50%),
    linear-gradient(180deg, var(--color-navy-deep) 0%, var(--color-slate-black) 100%);
  color: var(--color-white);
}

.hero__inner {
  padding-block: 64px 56px;
}

.hero__eyebrow {
  color: var(--color-cyan);
  font-size: 0.8125rem;
  letter-spacing: 0.16em;
  margin-bottom: 12px;
}

.hero__title {
  font-size: clamp(2rem, 1.5rem + 2.2vw, 3rem);
  margin-bottom: 20px;
}

.hero__lead {
  max-width: 42em;
  font-size: clamp(0.9375rem, 0.875rem + 0.3vw, 1.0625rem);
  font-weight: 700;
  color: var(--color-slate-light);
}

/* ---- 本棚セクション ---- */
.books {
  background-color: var(--color-slate-light);
}

.section-inner {
  padding-block: 56px;
}

.book-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 720px) {
  .book-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1040px) {
  .book-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.book-card {
  height: 100%;
  display: flex;
  flex-direction: column;
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  overflow: hidden;
}

.book-card__cover-wrap {
  aspect-ratio: 5 / 8;
  background-color: var(--color-slate-black);
}

.book-card__cover-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.book-card__cover-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  text-align: center;
  padding: 16px;
  color: var(--color-white);
  background:
    linear-gradient(155deg, var(--color-cobalt) 0%, var(--color-navy-deep) 65%),
    repeating-linear-gradient(
      45deg,
      rgba(255, 255, 255, 0.05) 0px,
      rgba(255, 255, 255, 0.05) 2px,
      transparent 2px,
      transparent 12px
    );
}

.book-card__cover-placeholder-label {
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  color: var(--color-cyan);
}

.book-card__cover-placeholder-title {
  max-width: 14em;
  font-size: clamp(1.25rem, 1rem + 0.8vw, 1.75rem);
  font-weight: 800;
  line-height: 1.5;
}

.book-card__body {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 24px;
}

.book-card__meta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.badge {
  display: inline-flex;
  align-items: center;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  padding: 4px 10px;
  border-radius: 999px;
}

.badge--series {
  background-color: rgba(37, 99, 235, 0.1);
  color: var(--color-cobalt);
}

.badge--tentative {
  background-color: rgba(23, 32, 51, 0.08);
  color: var(--color-text-muted);
}

.badge--status-available {
  background-color: rgba(37, 99, 235, 0.1);
  color: var(--color-cobalt);
}

.badge--status-coming-soon {
  background-color: rgba(23, 32, 51, 0.08);
  color: var(--color-text-muted);
}

.badge--status-in-review {
  background-color: rgba(34, 211, 238, 0.14);
  color: #075985;
}

.book-card__title {
  font-size: clamp(1.125rem, 1rem + 0.5vw, 1.375rem);
  color: var(--color-navy-deep);
}

.book-card__summary {
  color: var(--color-text-body);
  font-weight: 400;
}

.book-card__facts {
  display: grid;
  gap: 10px;
  margin: 0;
  font-size: 0.9375rem;
}

.book-card__facts dt {
  font-weight: 800;
  color: var(--color-navy-deep);
}

.book-card__facts dd {
  margin: 4px 0 0;
  font-weight: 400;
  color: var(--color-text-body);
}

.book-card__footer {
  margin-top: auto;
  padding-top: 8px;
  display: grid;
  gap: 10px;
}

.buy-button {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 58px;
  padding: 8px 20px;
  border-radius: var(--radius-md);
  background-color: var(--color-orange);
  color: var(--color-navy-deep);
  font-weight: 800;
  text-decoration: none;
  text-align: center;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.buy-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(251, 146, 60, 0.3);
}

.buy-button__sub {
  font-size: 0.75rem;
  font-weight: 700;
  line-height: 1.35;
  opacity: 0.78;
}

.status-note {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--color-text-muted);
  font-weight: 700;
  font-size: 0.9375rem;
}

/* ---- 読書順ガイド ---- */
.reading-order {
  background-color: var(--color-white);
}

.reading-order__lead {
  color: var(--color-text-muted);
  font-weight: 400;
  margin-bottom: 24px;
}

.reading-order__list {
  display: grid;
  gap: 16px;
}

.reading-order__item {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  padding: 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-slate-light);
}

.reading-order__number {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background-color: var(--color-navy-deep);
  color: var(--color-white);
  font-weight: 800;
}

.reading-order__title {
  color: var(--color-navy-deep);
  font-weight: 800;
  margin-bottom: 4px;
}

.reading-order__note {
  color: var(--color-text-body);
  font-weight: 400;
  font-size: 0.9375rem;
}

/* ---- 育てていく本棚 ---- */
.growing-bookshelf {
  background-color: var(--color-slate-light);
}

.growing-bookshelf__inner {
  max-width: 760px;
}

.growing-bookshelf__body {
  display: grid;
  gap: 12px;
  padding: 24px;
  border-left: 4px solid var(--color-cyan);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  background-color: var(--color-white);
  color: var(--color-text-body);
  font-weight: 400;
}

/* ---- フッター ---- */
.site-footer {
  background-color: var(--color-navy-deep);
  color: var(--color-slate-light);
}

.site-footer__inner {
  padding-block: 32px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 16px;
}

.site-footer__text {
  font-size: 0.875rem;
  font-weight: 400;
  color: rgba(243, 246, 250, 0.72);
}