:root {
  --bg: #faf7f2;
  --surface: #f0ebe2;
  --surface-2: #e6dfd1;
  --border: #d9d0bd;
  --border-strong: #c9bea8;
  --text: #1f2937;
  --text-muted: #6b7280;
  --accent: #6b8e6b;
  --accent-hover: #547254;
  --accent-2: #c87764;
  --success: #3d6b5a;
  --in-progress: #c87764;

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Fraunces', 'Iowan Old Style', Georgia, serif;

  --radius: 14px;
  --radius-sm: 8px;

  --shadow-sm: 0 1px 2px rgba(31, 41, 55, 0.04);
  --shadow-md: 0 1px 3px rgba(31, 41, 55, 0.04), 0 4px 16px rgba(31, 41, 55, 0.04);
  --shadow-lg: 0 4px 12px rgba(31, 41, 55, 0.05), 0 16px 40px rgba(31, 41, 55, 0.08);

  --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --container: 1200px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg);
  background-image:
    radial-gradient(at 8% -10%, rgba(107, 142, 107, 0.06) 0, transparent 45%),
    radial-gradient(at 92% 4%, rgba(200, 119, 100, 0.05) 0, transparent 45%);
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

/* ============ NAV ============ */

.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(250, 247, 242, 0.85);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 24px;
  max-width: var(--container);
  margin: 0 auto;
  position: relative;
}

.nav-brand {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.01em;
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.nav-brand::before {
  content: "";
  display: inline-block;
  width: 10px;
  height: 18px;
  border-radius: 2px;
  background: linear-gradient(160deg, var(--accent) 0%, var(--accent-2) 100%);
}

.nav-links {
  display: flex;
  gap: 32px;
  list-style: none;
  align-items: center;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  transition: color var(--transition);
  position: relative;
  padding: 4px 0;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent);
}

.nav-links a.active::after {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--accent);
  border-radius: 2px;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 12px;
  cursor: pointer;
  color: var(--text);
  font-size: 1rem;
  font-weight: 600;
}

/* ============ HERO ============ */

.hero {
  padding: clamp(72px, 12vw, 132px) 0 clamp(48px, 8vw, 88px);
  text-align: center;
}

.hero-eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--accent);
  background-color: rgba(107, 142, 107, 0.1);
  border: 1px solid rgba(107, 142, 107, 0.2);
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 28px;
}

.hero h1 {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: clamp(2.5rem, 6.5vw, 4.75rem);
  line-height: 1.05;
  letter-spacing: -0.025em;
  margin-bottom: 24px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-2) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
  max-width: 14ch;
  margin-left: auto;
  margin-right: auto;
}

.hero p {
  font-size: clamp(1.05rem, 1.6vw, 1.25rem);
  color: var(--text-muted);
  max-width: 620px;
  margin: 0 auto 40px;
  line-height: 1.6;
}

.btn-group {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 26px;
  border-radius: 10px;
  font-family: inherit;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition);
  border: 1px solid transparent;
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--accent);
  color: #fff;
  box-shadow: 0 1px 2px rgba(107, 142, 107, 0.2);
}

.btn-primary:hover {
  background-color: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(107, 142, 107, 0.28);
}

.btn-secondary {
  background-color: transparent;
  color: var(--text);
  border-color: var(--border-strong);
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
  background-color: rgba(107, 142, 107, 0.04);
}

/* ============ PAGE HEADER ============ */

.page-header {
  padding: clamp(56px, 9vw, 96px) 0 clamp(28px, 4vw, 48px);
  text-align: center;
}

.page-header .hero-eyebrow {
  margin-bottom: 20px;
}

.page-header h1 {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: clamp(2rem, 5vw, 3.5rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.page-header p {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto;
}

.page-note {
  max-width: 600px;
  margin: -8px auto clamp(32px, 5vw, 56px);
  text-align: center;
  font-size: 0.88rem;
  font-style: italic;
  color: var(--text-muted);
  line-height: 1.55;
}

.page-note em {
  font-style: normal;
  font-weight: 600;
  color: var(--text);
}

/* ============ SECTION ============ */

.section {
  padding: clamp(24px, 4vw, 48px) 0 clamp(64px, 10vw, 112px);
}

.section-divider {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 0 auto 32px;
  max-width: 200px;
  color: var(--text-muted);
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 0.95rem;
}

.section-divider::before,
.section-divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background-color: var(--border-strong);
}

/* ============ GRID ============ */

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

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

@media (max-width: 900px) {
  .grid,
  .grid-2 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 620px) {
  .grid,
  .grid-2 {
    grid-template-columns: 1fr;
  }
}

/* ============ FEATURE CARD (landing) ============ */

.feature-card {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  opacity: 0;
  transition: opacity var(--transition);
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-lg);
  background-color: var(--surface-2);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-eyebrow {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  margin-bottom: 4px;
}

.feature-card h3 {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.5rem;
  line-height: 1.2;
  color: var(--text);
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.97rem;
  line-height: 1.6;
}

.feature-arrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: auto;
  padding-top: 16px;
  color: var(--accent);
  font-weight: 600;
  font-size: 0.9rem;
  transition: gap var(--transition);
}

.feature-card:hover .feature-arrow {
  gap: 12px;
}

/* ============ BOOK CARD ============ */

.book-card {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  display: flex;
  flex-direction: column;
  gap: 18px;
  transition: all var(--transition);
}

.book-card:hover {
  transform: translateY(-3px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-lg);
  background-color: var(--surface-2);
}

.book-card-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.book-title-block {
  min-width: 0;
}

.book-title {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.4rem;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--text);
  margin-bottom: 6px;
}

.book-author {
  font-size: 0.93rem;
  color: var(--text-muted);
  font-style: italic;
}

.status {
  display: inline-block;
  padding: 5px 12px;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  white-space: nowrap;
  flex-shrink: 0;
}

.status-reading {
  background-color: rgba(200, 119, 100, 0.12);
  color: var(--in-progress);
  border: 1px solid rgba(200, 119, 100, 0.3);
}

.status-finished {
  background-color: rgba(61, 107, 90, 0.1);
  color: var(--success);
  border: 1px solid rgba(61, 107, 90, 0.25);
}

.status-queued {
  background-color: rgba(163, 120, 42, 0.12);
  color: #8a6420;
  border: 1px solid rgba(163, 120, 42, 0.3);
}

.status-ongoing-learning {
  background-color: rgba(66, 133, 175, 0.12);
  color: #2e6a9e;
  border: 1px solid rgba(66, 133, 175, 0.3);
}

.status-ongoing-workbook {
  background-color: rgba(130, 90, 160, 0.12);
  color: #6b3fa0;
  border: 1px solid rgba(130, 90, 160, 0.3);
}

.book-meta {
  margin-top: 6px;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.book-meta .tier {
  color: var(--accent);
  font-weight: 700;
}

.book-section ul.bullet-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.book-section ul.bullet-list li {
  position: relative;
  padding-left: 22px;
  margin-bottom: 8px;
  font-size: 0.94rem;
  line-height: 1.55;
  color: var(--text);
}

.book-section ul.bullet-list li:last-child {
  margin-bottom: 0;
}

.book-section ul.bullet-list li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-weight: 700;
}

.book-coming-soon {
  margin-top: 4px;
  padding-top: 14px;
  border-top: 1px dashed var(--border-strong);
  font-style: italic;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.book-section .book-placeholder {
  font-style: italic;
  font-size: 0.92rem;
  color: var(--text);
}

.book-section h4 {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  margin-bottom: 8px;
}

.book-section p {
  color: var(--text);
  font-size: 0.95rem;
  line-height: 1.6;
}

.book-section--brief p {
  font-size: 0.88rem;
  color: var(--text);
  line-height: 1.55;
}

/* ============ TIPS PAGE ============ */

.tips-coming-soon {
  text-align: center;
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 1.2rem;
  color: var(--text-muted);
  padding: clamp(48px, 8vw, 96px) 0;
}

.tips-stack {
  display: flex;
  flex-direction: column;
  gap: 24px;
  max-width: 820px;
  margin: 0 auto;
}

.tip-card {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px;
  transition: all var(--transition);
  position: relative;
}

.tip-card:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

.tip-number {
  position: absolute;
  top: 24px;
  right: 32px;
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 400;
  font-size: 2.5rem;
  color: var(--accent);
  opacity: 0.3;
  line-height: 1;
}

.tip-card h2 {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.6rem;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin-bottom: 16px;
  padding-right: 60px;
}

.tip-card > p {
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.7;
  margin-bottom: 16px;
}

.tip-card > p:last-child {
  margin-bottom: 0;
}

.tip-list {
  list-style: none;
  padding: 0;
}

.tip-list li {
  position: relative;
  padding-left: 24px;
  margin-bottom: 10px;
  color: var(--text-muted);
  line-height: 1.6;
}

.tip-list li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-weight: 700;
}

.tip-list li strong {
  color: var(--text);
  font-weight: 600;
}

/* ============ FOOTER ============ */

.footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: auto;
}

.footer a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.footer a:hover {
  text-decoration: underline;
}

/* ============ FADE-IN ANIMATION ============ */

@media (prefers-reduced-motion: no-preference) {
  .fade-up {
    opacity: 0;
    transform: translateY(16px);
    animation: fadeUp 600ms cubic-bezier(0.4, 0, 0.2, 1) forwards;
  }

  .fade-up.delay-1 { animation-delay: 80ms; }
  .fade-up.delay-2 { animation-delay: 160ms; }
  .fade-up.delay-3 { animation-delay: 240ms; }
  .fade-up.delay-4 { animation-delay: 320ms; }

  @keyframes fadeUp {
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }
}

/* ============ MOBILE NAV ============ */

@media (max-width: 720px) {
  .nav-toggle {
    display: inline-flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 4px;
    padding: 16px 24px 24px;
    align-items: stretch;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links li {
    width: 100%;
  }

  .nav-links a {
    display: block;
    padding: 10px 0;
    font-size: 1rem;
  }

  .nav-links a.active::after {
    display: none;
  }
}