/* ==========================================
   四叶草蓝星球 · 落地页
   Ocean Blue Design System
   ========================================== */

/* --- CSS Custom Properties (Design Tokens) --- */
:root {
  /* Ocean palette */
  --ocean-50:  #F0F9FF;
  --ocean-100: #E0F2FE;
  --ocean-200: #BAE6FD;
  --ocean-300: #7DD3FC;
  --ocean-400: #38BDF8;
  --ocean-500: #0EA5E9;
  --ocean-600: #0284C7;
  --ocean-700: #0369A1;
  --ocean-800: #075985;
  --ocean-900: #0C4A6E;
  --ocean-950: #082F49;

  /* Semantic */
  --sand:       #F59E0B;
  --white:      #FFFFFF;
  --text-primary:   var(--ocean-950);
  --text-secondary: var(--ocean-700);
  --text-muted:     var(--ocean-500);
  --bg-body:        var(--ocean-50);

  /* Layout */
  --max-width:  1200px;
  --nav-height: 64px;

  /* Typography */
  --font-heading:  "Playfair Display", Georgia, serif;
  --font-body:     "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;

  /* Shadows */
  --shadow-sm:  0 1px 3px rgba(8, 47, 73, 0.08);
  --shadow-md:  0 4px 12px rgba(8, 47, 73, 0.12);
  --shadow-lg:  0 12px 40px rgba(8, 47, 73, 0.16);
  --shadow-xl:  0 24px 64px rgba(8, 47, 73, 0.2);

  /* Radius */
  --radius-sm:  8px;
  --radius-md:  12px;
  --radius-lg:  20px;
  --radius-xl:  28px;

  /* Transitions */
  --ease-out:   cubic-bezier(0.22, 1, 0.36, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  color: var(--text-primary);
  background: var(--bg-body);
  line-height: 1.6;
  overflow-x: hidden;
}

img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }

/* ==========================================
   Nav
   ========================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(224, 242, 254, 0.85); /* ocean-100 at 85% */
  border-bottom: 1px solid rgba(186, 230, 253, 0.4); /* ocean-200 */
  transition: background 0.3s var(--ease-out),
              box-shadow 0.3s var(--ease-out);
}

.nav.scrolled {
  background: rgba(255, 255, 255, 0.95);
  box-shadow: var(--shadow-md);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--ocean-800);
  transition: color 0.2s;
}
.nav-logo:hover { color: var(--ocean-600); }
.nav-logo-icon { font-size: 1.4rem; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-link {
  padding: 8px 18px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--ocean-700);
  border-radius: var(--radius-sm);
  transition: color 0.2s, background 0.2s;
}
.nav-link:hover {
  color: var(--ocean-900);
  background: rgba(186, 230, 253, 0.4);
}

.nav-link-cta {
  color: var(--white);
  background: var(--ocean-500);
  padding: 8px 22px;
  margin-left: 4px;
}
.nav-link-cta:hover {
  background: var(--ocean-600);
  color: var(--white);
}

.nav-link-webapp {
  color: var(--white) !important;
  background: linear-gradient(135deg, var(--ocean-500), var(--ocean-600));
  padding: 8px 20px;
  border-radius: 9999px;
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(2, 132, 199, 0.3);
  transition: all 0.2s;
}
.nav-link-webapp:hover {
  background: linear-gradient(135deg, var(--ocean-600), var(--ocean-700));
  box-shadow: 0 4px 16px rgba(2, 132, 199, 0.5);
  transform: translateY(-1px);
  color: var(--white) !important;
}

/* 禁用按钮 */
.btn-disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* ==========================================
   Hero
   ========================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: calc(var(--nav-height) + 40px) 24px 80px;
  background: linear-gradient(175deg, #E0F2FE 0%, #BAE6FD 40%, #7DD3FC 75%, #0EA5E9 100%);
  overflow: hidden;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 560px;
  text-align: center;
}

.hero-badge {
  display: inline-block;
  padding: 6px 16px;
  margin-bottom: 24px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--ocean-700);
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: 100px;
  border: 1px solid rgba(255, 255, 255, 0.5);
}

.hero-title {
  font-family: var(--font-heading);
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 800;
  line-height: 1.12;
  color: var(--ocean-900);
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}
.hero-title-accent {
  color: var(--ocean-500);
  font-style: italic;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--ocean-700);
  line-height: 1.7;
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 48px;
}

.hero-stats {
  display: flex;
  gap: 32px;
  justify-content: center;
  padding-top: 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.4);
}

.hero-stat { text-align: center; }
.hero-stat-num {
  display: block;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--ocean-800);
}
.hero-stat-label {
  font-size: 0.8rem;
  color: var(--ocean-600);
  font-weight: 500;
}

.hero-visual {
  position: absolute;
  right: -60px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 1;
  display: none; /* hidden on mobile */
}

.hero-mockup {
  width: 420px;
  height: 300px;
  background: rgba(255, 255, 255, 0.25);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-radius: var(--radius-lg);
  border: 1px solid rgba(255, 255, 255, 0.4);
  padding: 16px;
  box-shadow: var(--shadow-xl);
  rotate: -4deg;
}

.hero-mockup-screen {
  width: 100%;
  height: 100%;
  background: var(--ocean-950);
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.hero-mockup-player {
  width: 90%;
  height: 60%;
  background: linear-gradient(135deg, var(--ocean-800), var(--ocean-600));
  border-radius: 6px;
  margin-bottom: 10px;
  position: relative;
}
.hero-mockup-player::after {
  content: "▶";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1.6rem;
  color: white;
  opacity: 0.8;
}

.hero-mockup-pet {
  font-size: 2.5rem;
  animation: pet-bounce 2s ease-in-out infinite;
}

@keyframes pet-bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}

/* Wave divider */
.hero-wave {
  position: absolute;
  bottom: -1px;
  left: 0;
  right: 0;
  z-index: 3;
  line-height: 0;
}
.hero-wave svg { width: 100%; height: auto; }

/* ==========================================
   Buttons
   ========================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 14px 32px;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
}

.btn-primary {
  background: var(--ocean-600);
  color: var(--white);
  box-shadow: 0 4px 16px rgba(2, 132, 199, 0.35);
}
.btn-primary:hover {
  background: var(--ocean-700);
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(2, 132, 199, 0.45);
}

.btn-outline {
  background: rgba(255, 255, 255, 0.7);
  color: var(--ocean-700);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.6);
}
.btn-outline:hover {
  background: rgba(255, 255, 255, 0.9);
  transform: translateY(-2px);
}

/* ==========================================
   Section Header (shared)
   ========================================== */
.section-header {
  text-align: center;
  margin-bottom: 56px;
}

.section-badge {
  display: inline-block;
  padding: 6px 16px;
  margin-bottom: 16px;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--ocean-600);
  background: var(--ocean-100);
  border-radius: 100px;
}

.section-title {
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 700;
  color: var(--ocean-900);
  line-height: 1.25;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--ocean-600);
}

/* ==========================================
   Features
   ========================================== */
.features {
  background: var(--ocean-50);
  padding: 100px 24px;
}

.features-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--white);
  border: 1px solid var(--ocean-200);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  transition: all 0.35s var(--ease-out);
  opacity: 0;
  transform: translateY(32px);
}

.feature-card.revealed {
  opacity: 1;
  transform: translateY(0);
}

.feature-card:hover {
  border-color: var(--ocean-300);
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}
.feature-card.revealed:hover {
  transform: translateY(-4px); /* override the animation transform */
}

.feature-icon {
  font-size: 2.4rem;
  margin-bottom: 16px;
}

.feature-title {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--ocean-800);
  margin-bottom: 8px;
}

.feature-desc {
  font-size: 0.92rem;
  color: var(--ocean-600);
  line-height: 1.7;
}

/* ==========================================
   Steps (3-step flow)
   ========================================== */
.steps {
  background: var(--ocean-100);
  padding: 100px 24px;
}

.steps-flow {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 0;
}

.step-item {
  flex: 0 1 280px;
  text-align: center;
  position: relative;
}

.step-number {
  width: 40px;
  height: 40px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--white);
  background: var(--ocean-500);
  border-radius: 50%;
}

.step-icon {
  font-size: 2.6rem;
  margin-bottom: 12px;
}

.step-title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--ocean-800);
  margin-bottom: 8px;
}

.step-desc {
  font-size: 0.9rem;
  color: var(--ocean-600);
  line-height: 1.7;
}

.step-connector {
  flex: 0 0 auto;
  display: flex;
  align-items: flex-start;
  padding-top: 56px;
}

/* ==========================================
   CTA (Download)
   ========================================== */
.cta {
  padding: 100px 24px;
  background: linear-gradient(175deg, #0EA5E9 0%, #0284C7 50%, #0369A1 100%);
  color: var(--white);
}

.cta-inner {
  max-width: 700px;
  margin: 0 auto;
  text-align: center;
}

.cta-badge {
  display: inline-block;
  padding: 6px 16px;
  margin-bottom: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: 100px;
  border: 1px solid rgba(255, 255, 255, 0.25);
}

.cta-title {
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 4.5vw, 2.8rem);
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 16px;
}

.cta-subtitle {
  font-size: 1.1rem;
  opacity: 0.85;
  margin-bottom: 40px;
  line-height: 1.7;
}

.cta-buttons {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 32px;
}

.btn-cta-primary {
  background: var(--white);
  color: var(--ocean-700);
  font-weight: 700;
  padding: 16px 36px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  transition: all 0.25s var(--ease-out);
}
.btn-cta-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-xl);
}

.btn-cta-secondary {
  background: rgba(255, 255, 255, 0.15);
  color: var(--white);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.25);
  padding: 16px 28px;
  border-radius: var(--radius-md);
  font-weight: 600;
  transition: all 0.25s var(--ease-out);
}
.btn-cta-secondary:hover {
  background: rgba(255, 255, 255, 0.25);
  transform: translateY(-2px);
}

.btn-icon { font-size: 1.1rem; }

.cta-version {
  font-size: 0.82rem;
  opacity: 0.6;
}

/* ==========================================
   Footer
   ========================================== */
.footer {
  background: var(--ocean-950);
  color: var(--ocean-200);
  padding: 72px 24px 32px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  gap: 64px;
  flex-wrap: wrap;
  margin-bottom: 48px;
}

.footer-brand { flex: 0 0 auto; }

.footer-logo {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 10px;
}

.footer-tagline {
  font-size: 0.9rem;
  color: var(--ocean-400);
  line-height: 1.6;
}

.footer-links {
  display: flex;
  gap: 64px;
  flex-wrap: wrap;
}

.footer-col h4 {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 14px;
}

.footer-col a {
  display: block;
  font-size: 0.88rem;
  color: var(--ocean-400);
  margin-bottom: 8px;
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--ocean-200); }

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  padding-top: 24px;
  border-top: 1px solid var(--ocean-800);
  text-align: center;
  font-size: 0.82rem;
  color: var(--ocean-500);
}

/* ==========================================
   Responsive
   ========================================== */

/* Tablet */
@media (max-width: 1024px) {
  .hero-visual { display: none; }
  .hero-content { max-width: 100%; }

  .steps-flow {
    flex-direction: column;
    align-items: center;
    gap: 0;
  }
  .step-item { flex: 0 0 auto; max-width: 380px; }
  .step-connector {
    padding-top: 8px;
    transform: rotate(90deg);
  }

  .footer-inner { flex-direction: column; gap: 40px; }
  .footer-links { gap: 40px; }
}

/* Mobile */
@media (max-width: 640px) {
  .nav-inner { padding: 0 16px; }
  .nav-links { gap: 4px; }
  .nav-link { padding: 6px 12px; font-size: 0.82rem; }
  .nav-link-cta { padding: 6px 16px; }

  .hero { padding: calc(var(--nav-height) + 24px) 16px 60px; }
  .hero-title { font-size: 2rem; }
  .hero-stats { flex-wrap: wrap; gap: 20px; }

  .features { padding: 64px 16px; }
  .features-grid { grid-template-columns: 1fr; }

  .steps { padding: 64px 16px; }

  .cta { padding: 64px 16px; }
  .cta-buttons { flex-direction: column; align-items: center; }

  .footer { padding: 48px 16px 24px; }
  .footer-links { flex-direction: column; gap: 28px; }
}