/* ============================================
   Book Hub: 自然に学ぶ、AI時代の経営哲学
   v1.1 — 二重入口モデル
   ============================================ */
/* --- Design Tokens --- */
:root {
    --color-engene-green: #2C5F3F;
    --color-burgundy: #8B1A3D;
    --color-earth-brown: #8B7355;
    --color-gold: #c9a84c;
    --color-green-deep: #1e3d20;
    --color-sumi-black: #1a1a1a;
    --color-bg-cream: #f7f4ed;
    --color-bg-warm: #f0ebe0;
    --color-light-stone: #e8e3d8;
    --color-paper: #faf7f0;
    --font-mincho: "Yu Mincho", "游明朝", "Hiragino Mincho ProN", serif;
    --font-sans: "Yu Gothic", "游ゴシック", "Hiragino Sans", sans-serif;
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-mincho);
    font-size: 1rem;
    line-height: 1.9;
    color: var(--color-sumi-black);
    background: var(--color-bg-cream);
    -webkit-font-smoothing: antialiased;
}

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

a {
    color: inherit;
    text-decoration: none;
}

ul {
    list-style: none;
}

.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* --- Header --- */
.site-header {
    background: var(--color-paper);
    border-bottom: 1px solid var(--color-light-stone);
    position: sticky;
    top: 0;
    z-index: 100;
}

.site-nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1080px;
    margin: 0 auto;
    padding: 0.9rem 1.5rem;
}

.site-nav__logo a {
    font-family: var(--font-mincho);
    font-size: 1.15rem;
    color: var(--color-engene-green);
    letter-spacing: 0.06em;
    font-weight: 600;
}

.site-nav__links {
    display: flex;
    gap: 1.8rem;
}

.site-nav__links a {
    font-family: var(--font-sans);
    font-size: 0.85rem;
    color: var(--color-sumi-black);
    letter-spacing: 0.03em;
    transition: color 0.25s;
}

.site-nav__links a:hover {
    color: var(--color-engene-green);
}

.hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    width: 28px;
    height: 20px;
    position: relative;
}

.hamburger span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--color-sumi-black);
    position: absolute;
    left: 0;
    transition: all 0.3s;
}

.hamburger span:nth-child(1) {
    top: 0;
}

.hamburger span:nth-child(2) {
    top: 9px;
}

.hamburger span:nth-child(3) {
    top: 18px;
}

.hamburger.is-open span:nth-child(1) {
    top: 9px;
    transform: rotate(45deg);
}

.hamburger.is-open span:nth-child(2) {
    opacity: 0;
}

.hamburger.is-open span:nth-child(3) {
    top: 9px;
    transform: rotate(-45deg);
}

/* --- Hero --- */
.hero {
    padding: 5rem 0 4rem;
    background: var(--color-bg-cream);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: "";
    position: absolute;
    top: -60px;
    right: -80px;
    width: 420px;
    height: 420px;
    background: radial-gradient(circle, rgba(201,168,76,0.06) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

.hero .container {
    display: flex;
    align-items: center;
    gap: 4rem;
}

.hero__cover {
    flex: 0 0 280px;
}

.hero__cover-img {
    width: 280px;
    border-radius: 4px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12), 0 2px 8px rgba(0, 0, 0, 0.08);
}

.hero__cover-placeholder {
    width: 280px;
    height: 400px;
    background: linear-gradient(135deg, var(--color-engene-green), var(--color-green-deep));
    border-radius: 4px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12), 0 2px 8px rgba(0, 0, 0, 0.08);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-paper);
    font-family: var(--font-mincho);
    font-size: 1.1rem;
    text-align: center;
    padding: 2rem;
    line-height: 1.8;
}

.hero__content {
    flex: 1;
}

.hero__title {
    font-family: var(--font-mincho);
    font-size: 2.4rem;
    font-weight: 500;
    color: var(--color-sumi-black);
    letter-spacing: 0.05em;
    line-height: 1.5;
}

.hero__tagline {
    font-family: var(--font-mincho);
    font-size: 2rem;
    color: var(--color-burgundy);
    letter-spacing: 0.1em;
    margin: 2rem 0 1.5rem;
}

.hero__description {
    font-size: 1.05rem;
    line-height: 2;
    color: var(--color-sumi-black);
}

.hero__note {
    margin-top: 1.5rem;
    font-size: 0.9rem;
    color: var(--color-earth-brown);
    line-height: 1.9;
}

/* --- Section Common --- */
.section-title {
    font-family: var(--font-mincho);
    font-size: 1.8rem;
    color: var(--color-engene-green);
    text-align: center;
    margin-bottom: 1rem;
    letter-spacing: 0.04em;
}

.section-lead {
    text-align: center;
    font-size: 0.95rem;
    color: var(--color-earth-brown);
    line-height: 2;
    margin-bottom: 3rem;
}

/* --- Path Overview (全体を俯瞰することから始める) --- */
.path-overview {
    background: var(--color-bg-cream);
    padding: 6rem 0;
}

/* --- Path Implementation (具体的な課題解決から始める) --- */
.path-implementation {
    background: var(--color-bg-warm);
    padding: 6rem 0;
}

/* --- Path Header (両セクション共通) --- */
.path-header {
    text-align: center;
    margin-bottom: 4rem;
}

.path-header__title {
    font-family: var(--font-mincho);
    font-size: 2rem;
    color: var(--color-engene-green);
    margin-bottom: 0.5rem;
    letter-spacing: 0.04em;
}

.path-header__subtitle {
    font-family: var(--font-mincho);
    font-size: 1.2rem;
    color: var(--color-gold);
    margin-bottom: 2rem;
    letter-spacing: 0.1em;
}

.path-header__lead {
    font-size: 1rem;
    line-height: 1.9;
    color: var(--color-sumi-black);
    margin-bottom: 1rem;
}

.path-header__sublead {
    font-size: 0.95rem;
    color: var(--color-earth-brown);
    font-style: italic;
}

/* --- Path Group (2つのツール / 2つのセッション) --- */
.path-group {
    margin-bottom: 4rem;
}

.path-group:last-child {
    margin-bottom: 0;
}

.path-group__title {
    font-family: var(--font-mincho);
    font-size: 1.6rem;
    color: var(--color-engene-green);
    text-align: center;
    margin-bottom: 0.3rem;
}

.path-group__subtitle {
    text-align: center;
    font-size: 1rem;
    color: var(--color-earth-brown);
    margin-bottom: 2rem;
    font-style: italic;
}

.path-group + .path-group {
    border-top: 1px solid var(--color-gold);
    padding-top: 4rem;
    margin-top: 4rem;
}

/* --- Path Cards --- */
.path-cards {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.path-card {
    background: var(--color-paper);
    padding: 2.5rem 2rem;
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    box-shadow: 0 2px 12px rgba(0,0,0,0.04);
    transition: box-shadow 0.3s, transform 0.3s;
}

.path-card:hover {
    box-shadow: 0 6px 24px rgba(0,0,0,0.08);
    transform: translateY(-3px);
}

.path-card--tool {
    border-left: 4px solid var(--color-engene-green);
}

.path-card--session {
    border-left: 4px solid var(--color-gold);
}

.path-card__visual {
    margin-bottom: 1.2rem;
}

.path-card__visual img {
    width: 240;
    height: 240;
    object-fit: contain;
}

.path-card__title {
    font-family: var(--font-mincho);
    font-size: 1.35rem;
    color: var(--color-sumi-black);
    margin-bottom: 0.3rem;
}

.path-card__subtitle {
    font-family: var(--font-mincho);
    font-size: 0.88rem;
    color: var(--color-earth-brown);
    margin-bottom: 1.2rem;
}

.path-card__description {
    font-size: 0.92rem;
    line-height: 1.9;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.path-card__meta {
    font-size: 0.85rem;
    margin-bottom: 1.8rem;
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0.3rem 1rem;
    line-height: 1.7;
}

.path-card__meta dt {
    font-family: var(--font-sans);
    font-weight: 600;
    color: var(--color-earth-brown);
}

.path-card__meta dd {
    color: var(--color-sumi-black);
}

.path-card__meta strong {
    color: var(--color-burgundy);
    font-weight: 600;
}

/* --- Buttons --- */
.btn {
    display: inline-block;
    font-family: var(--font-mincho);
    letter-spacing: 0.05em;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    border: none;
}

.btn--primary {
    background: var(--color-engene-green);
    color: var(--color-paper);
    padding: 0.9rem 2rem;
    border-radius: 4px;
}

.btn--primary:hover {
    background: var(--color-green-deep);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(44,95,63,0.25);
}

.btn--secondary {
    background: transparent;
    color: var(--color-engene-green);
    border: 1px solid var(--color-engene-green);
    padding: 0.9rem 2rem;
    border-radius: 4px;
}

.btn--secondary:hover {
    background: var(--color-engene-green);
    color: var(--color-paper);
}

.btn--text {
    background: transparent;
    color: var(--color-gold);
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--color-gold);
    border-radius: 0;
}

.btn--text:hover {
    color: var(--color-earth-brown);
    border-color: var(--color-earth-brown);
}

/* --- Inline Icon (arrows etc.) --- */
.icon-arrow {
    display: inline-block;
    width: 1em;
    height: 1em;
    vertical-align: -0.15em;
    margin-left: 0.45em;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    transition: transform 0.25s ease;
}

.btn:hover .icon-arrow--right,
a:hover .icon-arrow--right {
    transform: translateX(3px);
}

.btn:hover .icon-arrow--down,
a:hover .icon-arrow--down {
    transform: translateY(3px);
}

/* --- Banner Grid (パワーワードバナー) --- */
.banner-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.banner-card {
    display: block;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    transition: transform 0.3s, box-shadow 0.3s;
}

.banner-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.banner-card img {
    width: 100%;
    height: auto;
    border-radius: 8px;
}

.banner-card--text {
    background: linear-gradient(135deg, var(--color-green-deep), var(--color-engene-green));
    color: var(--color-paper);
    padding: 2.5rem 1.5rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    justify-content: center;
    min-height: 220px;
}

.banner-card__title {
    font-family: var(--font-mincho);
    font-size: 1.3rem;
    letter-spacing: 0.08em;
    margin-bottom: 0.8rem;
}

.banner-card__subtitle {
    font-size: 0.88rem;
    opacity: 0.85;
    margin-bottom: 1.2rem;
    letter-spacing: 0.05em;
}

.banner-card__footer {
    font-family: var(--font-sans);
    font-size: 0.78rem;
    opacity: 0.7;
    letter-spacing: 0.04em;
}

/* --- Further --- */
.further {
    padding: 5rem 0;
    background: var(--color-bg-cream);
}

.further-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.further-card {
    background: var(--color-paper);
    border-radius: 6px;
    padding: 2.5rem 2rem;
    box-shadow: 0 2px 12px rgba(0,0,0,0.04);
    border-top: 3px solid var(--color-light-stone);
}

.further-card__title {
    font-family: var(--font-mincho);
    font-size: 1.25rem;
    color: var(--color-sumi-black);
    margin-bottom: 1rem;
}

.further-card__description {
    font-size: 0.92rem;
    line-height: 1.9;
    margin-bottom: 1.5rem;
}

.further-card__meta {
    font-size: 0.85rem;
    margin-bottom: 1.8rem;
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0.3rem 1rem;
    line-height: 1.7;
}

.further-card__meta dt {
    font-family: var(--font-sans);
    font-weight: 600;
    color: var(--color-earth-brown);
}

.further-card__meta dd {
    color: var(--color-sumi-black);
}

/* --- Author --- */
.author {
    padding: 5rem 0;
    background: var(--color-bg-warm);
    position: relative;
}

.author .container {
    display: flex;
    align-items: flex-start;
    gap: 3rem;
}

.author__photo {
    flex: 0 0 200px;
}

.author__photo img {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}

.author__photo-placeholder {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: var(--color-light-stone);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-mincho);
    font-size: 0.85rem;
    color: var(--color-earth-brown);
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}

.author__content {
    flex: 1;
}

.author__role {
    font-family: var(--font-mincho);
    font-size: 0.9rem;
    color: var(--color-gold);
    letter-spacing: 0.08em;
    margin-bottom: 0.3rem;
    font-weight: 400;
}

.author__name {
    font-family: var(--font-mincho);
    font-size: 1.6rem;
    color: var(--color-sumi-black);
    margin-bottom: 0.8rem;
    font-weight: 500;
}

.author__title {
    font-size: 0.88rem;
    color: var(--color-earth-brown);
    line-height: 1.8;
    margin-bottom: 1.2rem;
}

.author__bio {
    font-size: 0.92rem;
    line-height: 2;
    margin-bottom: 1.5rem;
}

/* --- More Resources --- */
.more-resources {
    padding: 5rem 0;
    background: var(--color-bg-warm);
}

.resource-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.resource-link {
    display: block;
    background: var(--color-paper);
    border-radius: 6px;
    padding: 2rem 1.5rem;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0,0,0,0.04);
    transition: box-shadow 0.3s, transform 0.3s;
    border-bottom: 2px solid transparent;
}

.resource-link:hover {
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    transform: translateY(-2px);
    border-bottom-color: var(--color-gold);
}

.resource-link__name {
    font-family: var(--font-mincho);
    font-size: 1.1rem;
    color: var(--color-engene-green);
    margin-bottom: 0.5rem;
    letter-spacing: 0.04em;
}

.resource-link__desc {
    font-size: 0.85rem;
    color: var(--color-earth-brown);
    line-height: 1.7;
}

/* --- Footer --- */
.site-footer {
    background: var(--color-green-deep);
    color: var(--color-light-stone);
    padding: 3.5rem 0 2rem;
    text-align: center;
}

.footer__title {
    font-family: var(--font-mincho);
    font-size: 1.1rem;
    color: var(--color-paper);
    letter-spacing: 0.06em;
    margin-bottom: 0.3rem;
}

.footer__subtitle {
    font-size: 0.82rem;
    color: var(--color-earth-brown);
    letter-spacing: 0.05em;
    margin-bottom: 2rem;
}

.footer__links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.footer__links a {
    font-family: var(--font-sans);
    font-size: 0.8rem;
    color: var(--color-light-stone);
    transition: color 0.25s;
    letter-spacing: 0.03em;
}

.footer__links a:hover {
    color: var(--color-gold);
}

.footer__copyright {
    font-size: 0.72rem;
    color: var(--color-earth-brown);
    letter-spacing: 0.04em;
}


/* ---- Book CTA card ------------------------------------------------------ */

.book-card {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  background-color: #FFFDFC;
  border: 1px solid rgba(184, 146, 60, 0.15);
  border-left: 5px solid var(--color-gold);
  border-radius: 12px;
  padding: 2.25rem 2.5rem;
  margin: 2.5rem 0;
  box-shadow: 0 8px 24px rgba(107, 79, 31, 0.04);
  align-items: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.book-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(107, 79, 31, 0.07);
}

@media (min-width: 768px) {
  .book-card {
    grid-template-columns: 130px 1fr;
    gap: 2.5rem;
  }
}

.book-card__cover {
  display: flex;
  justify-content: center;
  align-items: center;
}

.book-cover-img {
  width: 110px;
  max-width: 110px;
  height: auto;
  border-radius: 4px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.12),
              0 2px 6px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s ease;
}

.book-card:hover .book-cover-img {
  transform: scale(1.03) rotate(-1deg);
}

.book-card__title {
  color: var(--color-engene-green);
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 0.35rem;
  letter-spacing: 0.02em;
}

.book-card__subtitle {
  color: var(--color-earth-brown);
  font-family: var(--font-mincho);
  font-size: 0.95rem;
  font-weight: 500;
  margin-bottom: 0.75rem;
  letter-spacing: 0.03em;
}

.book-card__desc {
  color: #555;
  font-size: 0.88rem;
  line-height: 1.65;
  margin-bottom: 1.25rem;
}

.btn--amazon {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.icon-amazon {
  width: 1.25rem;
  height: 1.25rem;
  max-width: 1.25rem;
  max-height: 1.25rem;
  min-width: 1.25rem;
  min-height: 1.25rem;
}
@media (max-width: 600px) {
  .card {
    padding: 1.5rem 1.25rem;
  }

  .download-cta {
    padding: 1.5rem 1rem;
  }

  .btn--large {
    font-size: 0.95rem;
    padding: 0.85rem 1.25rem;
  }

  .book-card {
    padding: 1.5rem 1.25rem;
  }

  .book-cover-img {
    width: 90px;
    max-width: 90px;
  }

  .book-card__title {
    font-size: 1.1rem;
  }

  .book-card__desc {
    font-size: 0.85rem;
  }
}

.card--thanks {
  padding: 4rem 3rem;
}

.card-title {
  font-size: 1.6rem;
  color: var(--color-forest);
  margin-bottom: 1.25rem;
  position: relative;
  padding-bottom: 0.5rem;
}

.card-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 40px;
  height: 3px;
  background: var(--color-earth-light);
  border-radius: 2px;
}

.card-subtitle {
  font-size: 1.5rem;
  color: var(--color-forest);
  margin-bottom: 1.5rem;
}

.card-section-title {
  font-size: 1.25rem;
  color: var(--color-forest);
  margin-bottom: 1rem;
}


/* --- Responsive: Tablet --- */
@media (max-width: 1023px) {
    .hero__title {
        font-size: 2rem;
    }

    .hero__tagline {
        font-size: 1.6rem;
    }

    .hero .container {
        gap: 2.5rem;
    }

    .hero__cover {
        flex: 0 0 220px;
    }

    .hero__cover-img,
    .hero__cover-placeholder {
        width: 220px;
    }

    .hero__cover-placeholder {
        height: 315px;
    }

    .path-cards {
        grid-template-columns: repeat(2, 1fr);
    }

    .further-list {
        grid-template-columns: 1fr;
    }

    .banner-grid {
        grid-template-columns: 1fr;
        max-width: 500px;
        margin: 0 auto;
    }

    .resource-links {
        grid-template-columns: 1fr;
        max-width: 480px;
        margin: 0 auto;
    }
}

/* --- Responsive: Mobile --- */
@media (max-width: 767px) {
    .site-nav__links {
        display: none;
    }

    .site-nav__links.is-open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--color-paper);
        padding: 1rem 1.5rem 1.5rem;
        border-bottom: 1px solid var(--color-light-stone);
        gap: 1rem;
        box-shadow: 0 4px 16px rgba(0,0,0,0.06);
    }

    .hamburger {
        display: block;
    }

    .hero {
        padding: 3rem 0;
    }

    .hero .container {
        flex-direction: column;
        align-items: center;
        text-align: center;
        gap: 2rem;
    }

    .hero__cover {
        flex: none;
    }

    .hero__cover-img,
    .hero__cover-placeholder {
        width: 200px;
        margin: 0 auto;
    }

    .hero__cover-placeholder {
        height: 286px;
        font-size: 0.95rem;
    }

    .hero__title {
        font-size: 1.6rem;
    }

    .hero__tagline {
        font-size: 1.35rem;
        margin: 1.2rem 0 1rem;
    }

    .hero__description {
        font-size: 0.95rem;
    }

    .section-title {
        font-size: 1.4rem;
    }

    .section-lead {
        font-size: 0.88rem;
    }

    .path-overview,
    .path-implementation {
        padding: 4rem 0;
    }

    .path-header {
        margin-bottom: 3rem;
    }

    .path-header__title {
        font-size: 1.5rem;
    }

    .path-header__subtitle {
        font-size: 1rem;
    }

    .path-group__title {
        font-size: 1.3rem;
    }

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

    .path-card {
        padding: 2rem 1.5rem;
    }

    .further-list {
        grid-template-columns: 1fr;
    }

    .author .container {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .author__photo {
        flex: none;
    }

    .footer__links {
        gap: 1.2rem;
    }
}