/* ===========================
   YIDI 一滴 — PREMIUM DESIGN SYSTEM v2
   Apple/Tesla-grade quality. Serene, restrained, every pixel breathes.
   Cinematic sections. Generous whitespace. Scroll-driven reveals.
   =========================== */

:root {
  /* Palette: ink green, earth brown/amber, water blue, warm cream */
  --ink-green: #2D4A35;
  --ink-green-light: #3A5A40;
  --ink-green-subtle: #EEF3EF;
  --ink-green-wash: #F5F8F5;
  --amber-gold: #B08D57;
  --amber-gold-subtle: #F6F0E8;
  --water-blue: #5A8FA8;
  --water-blue-subtle: #EDF4F7;
  /* Backgrounds */
  --bg: #FAFAF7;
  --bg-warm: #F5F3EE;
  --bg-card: #FFFFFF;
  --bg-dark: #1A1A1A;
  /* Text hierarchy */
  --fg: #111111;
  --fg-secondary: #3A3A3A;
  --fg-muted: #6B6B6B;
  --fg-dim: #999999;
  --fg-light: #FFFFFF;
  /* Structure */
  --border: #E0DCD4;
  --border-subtle: #EEEBE4;
  --radius: 16px;
  --radius-sm: 10px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.03);
  --shadow-md: 0 8px 32px rgba(0,0,0,0.04);
  --shadow-lg: 0 16px 64px rgba(0,0,0,0.06);
  --shadow-hero: 0 24px 80px rgba(0,0,0,0.08);
  /* Spacing — Apple-like generous whitespace */
  --space-xs: 8px;
  --space-sm: 16px;
  --space-md: 24px;
  --space-lg: 48px;
  --space-xl: 80px;
  --space-2xl: 120px;
  --space-3xl: 160px;
  --space-4xl: 200px;
  /* Layout */
  --max-width: 1200px;
  --content-narrow: 780px;
  --content-tight: 600px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background: var(--bg);
  color: var(--fg);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Noto Sans SC', 'Helvetica Neue', sans-serif;
  font-weight: 400;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  text-rendering: optimizeLegibility;
}

/* ---- Typography — Apple-grade Hierarchy ---- */
h1, h2, h3, h4 {
  font-family: 'Noto Serif SC', 'Source Serif 4', Georgia, serif;
  line-height: 1.2;
  letter-spacing: -0.025em;
  color: var(--fg);
  font-weight: 600;
}

/* ---- Selection ---- */
::selection {
  background: rgba(45, 74, 53, 0.12);
  color: var(--fg);
}

/* ---- Smooth Scroll Offset ---- */
[id] {
  scroll-margin-top: 80px;
}

/* ---- Layout ---- */
.section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ---- Navbar — Glass Morphism ---- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(250, 250, 247, 0.72);
  backdrop-filter: blur(32px) saturate(1.4);
  -webkit-backdrop-filter: blur(32px) saturate(1.4);
  border-bottom: 1px solid rgba(0,0,0,0.04);
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

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

.nav-logo {
  font-family: 'Noto Serif SC', serif;
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--fg);
  text-decoration: none;
  letter-spacing: 0.01em;
  display: flex;
  align-items: center;
  gap: 10px;
  transition: opacity 0.2s ease;
}

.nav-logo:hover {
  opacity: 0.7;
}

.nav-logo .drop {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--ink-green);
  display: inline-block;
  animation: dropPulse 3s ease-in-out infinite;
}

@keyframes dropPulse {
  0%, 100% { opacity: 0.5; transform: scale(1); }
  50% { opacity: 0.9; transform: scale(1.2); }
}

.nav-cta {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--fg-secondary);
  padding: 8px 22px;
  border: 1px solid var(--border);
  border-radius: 100px;
  text-decoration: none;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  letter-spacing: 0.02em;
}

.nav-cta:hover {
  color: var(--ink-green);
  border-color: var(--ink-green);
  background: var(--ink-green-subtle);
}

/* ---- Hero — Cinematic, Full-viewport ---- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 160px 0 var(--space-2xl);
  overflow: hidden;
  text-align: center;
}

.hero::before {
  content: '';
  position: absolute;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 1200px;
  height: 1200px;
  background: radial-gradient(circle, rgba(45,74,53,0.03) 0%, transparent 60%);
  pointer-events: none;
}

.hero-inner {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  position: relative;
  z-index: 1;
}

.hero-eyebrow {
  margin-bottom: var(--space-lg);
}

.eyebrow-tag {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--amber-gold);
  padding: 0;
  opacity: 1;
}

.hero-headline {
  font-size: clamp(3rem, 7.5vw, 5rem);
  font-weight: 600;
  color: var(--fg);
  margin-bottom: var(--space-lg);
  line-height: 1.08;
  letter-spacing: -0.04em;
}

.hero-sub-cn {
  font-size: 1.15rem;
  color: var(--fg-muted);
  line-height: 2;
  max-width: var(--content-tight);
  margin: 0 auto var(--space-sm);
  font-weight: 400;
}

.hero-sub-en {
  font-size: 0.88rem;
  color: var(--fg-dim);
  line-height: 1.8;
  max-width: 520px;
  margin: 0 auto var(--space-xl);
  font-style: italic;
  font-family: 'Inter', sans-serif;
}

.hero-actions {
  margin-top: var(--space-md);
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--ink-green);
  color: #fff;
  font-size: 0.95rem;
  font-weight: 500;
  padding: 18px 48px;
  border-radius: 100px;
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  letter-spacing: 0.01em;
  font-family: 'Inter', 'Noto Sans SC', sans-serif;
}

.hero-cta:hover {
  background: var(--ink-green-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(45,74,53,0.25);
}

.hero-cta-sub {
  display: block;
  margin-top: var(--space-sm);
  font-size: 0.75rem;
  color: var(--fg-dim);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

/* Hero Image — Cinematic crop */
.hero-visual {
  max-width: var(--max-width);
  margin: var(--space-2xl) auto 0;
  padding: 0 var(--space-lg);
}

.hero-image {
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-hero);
  position: relative;
}

.hero-image::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  box-shadow: inset 0 0 0 1px rgba(0,0,0,0.06);
  pointer-events: none;
}

.hero-image img {
  width: 100%;
  height: auto;
  display: block;
  max-height: 520px;
  object-fit: cover;
  transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.hero-image:hover img {
  transform: scale(1.02);
}

/* ---- Section Label — Shared ---- */
.section-label {
  display: block;
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--amber-gold);
  margin-bottom: var(--space-md);
  font-family: 'Inter', sans-serif;
}

.section-sub {
  font-size: 1rem;
  color: var(--fg-muted);
  margin-top: 12px;
  line-height: 1.9;
}

/* ---- Features Section — Three Pillars ---- */
.values {
  padding: var(--space-4xl) 0 var(--space-3xl);
}

.values-header {
  text-align: center;
  max-width: var(--content-narrow);
  margin: 0 auto var(--space-2xl);
}

.values-header h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.values-header .sub {
  font-size: 1rem;
  color: var(--fg-muted);
  margin-top: 8px;
  line-height: 1.9;
  font-style: italic;
  font-family: 'Inter', sans-serif;
}

.values-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
}

.value-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: var(--space-lg);
  border: 1px solid var(--border-subtle);
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  position: relative;
  overflow: hidden;
}

.value-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--ink-green);
  opacity: 0;
  transition: opacity 0.4s ease;
}

.value-card:hover {
  border-color: var(--border);
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
}

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

.value-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  margin-bottom: var(--space-md);
}

.value-icon--green {
  background: var(--ink-green-subtle);
}

.value-icon--warm {
  background: var(--amber-gold-subtle);
}

.value-icon--blue {
  background: var(--water-blue-subtle);
}

.value-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 6px;
  line-height: 1.4;
}

.value-card .en-label {
  font-size: 0.68rem;
  color: var(--fg-dim);
  margin-bottom: var(--space-sm);
  font-family: 'Inter', sans-serif;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.value-card p {
  font-size: 0.9rem;
  color: var(--fg-muted);
  line-height: 1.8;
}

/* ---- How it Works — Elegant Process ---- */
.howitworks {
  padding: var(--space-3xl) 0;
  background: var(--bg-warm);
  position: relative;
}

.howitworks::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
}

.hiw-header {
  text-align: center;
  max-width: var(--content-narrow);
  margin: 0 auto var(--space-2xl);
}

.hiw-header h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.hiw-header .sub {
  font-size: 1rem;
  color: var(--fg-muted);
  margin-top: 8px;
  line-height: 1.9;
  font-style: italic;
  font-family: 'Inter', sans-serif;
}

.steps-row {
  max-width: 920px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
  position: relative;
}

.steps-row::before {
  content: '';
  position: absolute;
  top: 24px;
  left: calc(12.5% + 14px);
  right: calc(12.5% + 14px);
  height: 1px;
  background: var(--border);
}

.step {
  background: transparent;
  border: none;
  border-radius: 0;
  padding: 0;
  text-align: center;
  position: relative;
  box-shadow: none;
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 2px solid var(--ink-green);
  color: var(--ink-green);
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  font-size: 0.7rem;
  margin-bottom: var(--space-md);
  position: relative;
  z-index: 1;
  transition: all 0.3s ease;
}

.step:hover .step-num {
  background: var(--ink-green);
  color: #fff;
}

.step h3 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.step .en-label {
  font-size: 0.65rem;
  color: var(--fg-dim);
  margin-bottom: var(--space-xs);
  font-family: 'Inter', sans-serif;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.step p {
  font-size: 0.85rem;
  color: var(--fg-muted);
  line-height: 1.7;
}

/* ---- Product Preview — 七天实修营 ---- */
.product-preview {
  padding: var(--space-3xl) 0;
}

.product-preview::before {
  content: '';
  display: block;
  width: 1px;
  height: 0;
}

.product-header {
  text-align: center;
  max-width: var(--content-narrow);
  margin: 0 auto var(--space-2xl);
}

.product-header h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.product-header .desc {
  font-size: 1rem;
  color: var(--fg-muted);
  line-height: 1.9;
}

.product-header .desc-en {
  font-size: 0.88rem;
  color: var(--fg-dim);
  margin-top: 8px;
  font-style: italic;
  font-family: 'Inter', sans-serif;
}

/* Day list — refined list */
.pp-day-list {
  max-width: 680px;
  margin: 0 auto;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.pp-day {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: 20px var(--space-md);
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-subtle);
  transition: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

.pp-day:hover {
  border-color: var(--ink-green);
  box-shadow: var(--shadow-sm);
  transform: translateX(6px);
  background: var(--ink-green-wash);
}

.pp-day .day-num {
  font-family: 'Source Serif 4', 'Noto Serif SC', Georgia, serif;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--ink-green);
  width: 32px;
  flex-shrink: 0;
  opacity: 0.6;
}

.pp-day .day-title {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--fg);
}

.pp-day .day-title-en {
  font-size: 0.75rem;
  color: var(--fg-dim);
  margin-left: 8px;
  font-family: 'Inter', sans-serif;
}

.pp-day .day-dur {
  margin-left: auto;
  font-size: 0.72rem;
  color: var(--fg-dim);
  white-space: nowrap;
  font-family: 'Inter', sans-serif;
  letter-spacing: 0.02em;
}

/* ---- Audience Section ---- */
.audience-section {
  padding: var(--space-3xl) 0;
  background: var(--bg-warm);
  position: relative;
}

.audience-section::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
}

.audience-inner {
  max-width: var(--content-narrow);
  margin: 0 auto;
  text-align: center;
}

.audience-inner h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  margin-bottom: var(--space-md);
}

.audience-inner .desc {
  font-size: 1.08rem;
  color: var(--fg-muted);
  line-height: 2;
  margin-bottom: var(--space-xl);
}

.audience-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

.audience-tag {
  padding: 10px 24px;
  border-radius: 100px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  font-size: 0.82rem;
  color: var(--fg-muted);
  transition: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  cursor: default;
}

.audience-tag:hover {
  border-color: var(--ink-green);
  color: var(--ink-green);
  background: var(--ink-green-subtle);
  transform: translateY(-2px);
}

/* ---- Closing CTA — Apple-like Grand Finale ---- */
.closing-section {
  padding: var(--space-4xl) 0 var(--space-3xl);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.closing-section::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 1000px;
  height: 600px;
  background: radial-gradient(circle at center bottom, rgba(45,74,53,0.04) 0%, transparent 70%);
  pointer-events: none;
}

.closing-content {
  max-width: var(--content-narrow);
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.closing-content h2 {
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 600;
  margin-bottom: var(--space-md);
  line-height: 1.15;
}

.closing-content .sub {
  font-size: 1.05rem;
  color: var(--fg-muted);
  line-height: 2;
  max-width: 520px;
  margin: 0 auto var(--space-xl);
}

.closing-content .sub em {
  font-style: italic;
  color: var(--fg-dim);
  font-family: 'Inter', sans-serif;
  font-size: 0.92rem;
}

.closing-cta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: var(--ink-green);
  color: #fff;
  font-size: 1.05rem;
  font-weight: 500;
  padding: 20px 56px;
  border-radius: 100px;
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  letter-spacing: 0.01em;
  font-family: 'Inter', 'Noto Sans SC', sans-serif;
}

.closing-cta:hover {
  background: var(--ink-green-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(45,74,53,0.25);
}

.closing-note {
  margin-top: var(--space-sm);
  font-size: 0.75rem;
  color: var(--fg-dim);
  letter-spacing: 0.04em;
}

/* ---- Footer — Restrained ---- */
.site-footer {
  padding: var(--space-lg) 0 var(--space-md);
  border-top: 1px solid var(--border-subtle);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-logo {
  font-family: 'Noto Serif SC', serif;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--fg-secondary);
  letter-spacing: 0.02em;
}

.footer-tagline {
  font-size: 0.75rem;
  color: var(--fg-dim);
  font-family: 'Inter', sans-serif;
  letter-spacing: 0.02em;
}

/* ---- Scroll-triggered Reveals ---- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(32px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

.reveal {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* Legacy animation classes — still used in templates */
.animate-in {
  animation: fadeInUp 0.9s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.delay-1 { animation-delay: 0.15s; }
.delay-2 { animation-delay: 0.3s; }
.delay-3 { animation-delay: 0.45s; }
.delay-4 { animation-delay: 0.6s; }

/* ---- Responsive ---- */
@media (max-width: 768px) {
  :root {
    --space-lg: 28px;
    --space-xl: 56px;
    --space-2xl: 80px;
    --space-3xl: 110px;
    --space-4xl: 140px;
  }

  .hero {
    min-height: auto;
    padding: 140px 0 var(--space-xl);
  }

  .section-inner, .nav-inner, .hero-inner {
    padding: 0 20px;
  }

  .hero-visual { padding: 0 20px; }

  .values-grid { grid-template-columns: 1fr; gap: var(--space-sm); }

  .steps-row {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-md);
  }
  .steps-row::before { display: none; }

  .footer-inner {
    flex-direction: column;
    align-items: center;
    gap: var(--space-sm);
    text-align: center;
  }

  .audience-tags { gap: 8px; }
}

@media (max-width: 480px) {
  .hero-headline { font-size: 2.4rem; }
  .steps-row { grid-template-columns: 1fr; }
  .audience-tag { font-size: 0.78rem; padding: 8px 18px; }
  .hero-cta { padding: 16px 36px; font-size: 0.9rem; }
  .closing-cta { padding: 16px 40px; font-size: 0.95rem; }
}