/*
 * Kashi Landing - Editorial + 东方克制
 * 脱离 AI 感、超高级感
 */

@import url('https://fonts.googleapis.com/css2?family=Fraunces:opsz,wght@9..144,400;9..144,600;9..144,700&family=Noto+Serif+SC:wght@400;600;700&family=Noto+Sans+SC:wght@300;400;500&display=swap');

:root {
  --bg: #faf8f5;
  --bg-subtle: #f5f2ed;
  --text: #1c1917;
  --text-muted: #57534e;
  --accent: #3d3a36;
  --accent-soft: #78716c;
  --accent-warm: #a16207;
  --border: rgba(28, 25, 23, 0.08);
  --golden: 1.618;
  --font-display: 'Fraunces', 'Noto Serif SC', 'Songti SC', 'SimSun', serif;
  --font-body: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-weight: 400;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.6;
  overflow-x: hidden;
}

/* Noise overlay for texture */
.landing::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  opacity: 0.03;
  pointer-events: none;
  z-index: 0;
}

.landing {
  position: relative;
  z-index: 1;
}

main {
  position: relative;
}

/* Language switcher - icon + dropdown */
.landing-lang-switch {
  position: absolute;
  top: 1.5rem;
  right: clamp(1.5rem, 6vw, 6rem);
  z-index: 20;
}
.landing-lang-trigger {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text-muted);
  transition: color 0.2s ease;
}
.landing-lang-trigger:hover {
  color: var(--text);
}
.landing-lang-icon {
  width: 1.25rem;
  height: 1.25rem;
  opacity: 0.6;
  transition: opacity 0.2s ease;
}
.landing-lang-trigger:hover .landing-lang-icon {
  opacity: 1;
}
.landing-lang-dropdown {
  position: absolute;
  top: calc(100% + 0.5rem);
  right: 0;
  min-width: 8rem;
  padding: 0.35rem 0;
  background: var(--bg);
  border: 1px solid var(--border);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  pointer-events: none;
  transition: opacity 0.2s ease, visibility 0.2s ease, transform 0.2s ease;
}
.landing-lang-switch.is-open .landing-lang-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  pointer-events: auto;
}
.landing-lang-dropdown a {
  display: block;
  padding: 0.5rem 1rem;
  font-size: 0.8125rem;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s ease, background 0.2s ease;
}
.landing-lang-dropdown a:hover {
  color: var(--text);
  background: var(--bg-subtle);
}
.landing-lang-dropdown a.is-active {
  color: var(--text);
  font-weight: 600;
  background: var(--bg-subtle);
  border-left: 3px solid var(--accent-soft);
}

/* Hero */
.hero {
  min-height: calc(100vh - 80px);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: clamp(3rem, 10vw, 8rem) clamp(1.5rem, 6vw, 6rem);
  position: relative;
}

.hero-content {
  max-width: 720px;
}

.hero-label {
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
  opacity: 0;
  animation: fadeUp 0.8s ease forwards;
  animation-delay: 0.1s;
  animation-fill-mode: both;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 8vw, 4.5rem);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--text);
  margin-bottom: 1rem;
  opacity: 0;
  animation: fadeUp 0.8s ease forwards;
  animation-delay: 0.2s;
  animation-fill-mode: both;
}

.hero-subtitle {
  font-family: var(--font-body);
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  font-weight: 300;
  color: var(--text-muted);
  max-width: 32ch;
  margin-bottom: 2.5rem;
  opacity: 0;
  animation: fadeUp 0.8s ease forwards;
  animation-delay: 0.35s;
  animation-fill-mode: both;
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--text);
  text-decoration: none;
  padding: 0.75rem 1.5rem;
  border: 1px solid var(--border);
  background: transparent;
  transition: border-color 0.3s ease, background 0.3s ease;
  opacity: 0;
  animation: fadeUp 0.8s ease forwards;
  animation-delay: 0.5s;
  animation-fill-mode: both;
}

.hero-cta:hover {
  border-color: var(--accent-soft);
  background: var(--bg-subtle);
}

/* Hero visual - abstract book/language shape */
.hero-visual {
  position: absolute;
  right: clamp(2rem, 8vw, 10rem);
  top: 50%;
  transform: translateY(-50%);
  width: clamp(180px, 28vw, 320px);
  height: clamp(180px, 28vw, 320px);
  opacity: 0;
  animation: fadeUp 1s ease forwards;
  animation-delay: 0.4s;
  animation-fill-mode: both;
}

.hero-visual svg {
  width: 100%;
  height: 100%;
  opacity: 0.85;
}

@media (max-width: 900px) {
  .hero-visual {
    position: relative;
    right: auto;
    top: auto;
    transform: none;
    margin-top: 3rem;
    align-self: flex-start;
  }
}

/* Features */
.features {
  padding: clamp(4rem, 12vw, 8rem) clamp(1.5rem, 6vw, 6rem);
}

.features-inner {
  max-width: 1000px;
  margin: 0 auto;
}

.features-title {
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 3vw, 1.5rem);
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  margin-bottom: 2.5rem;
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.features-inner.is-visible .features-title {
  opacity: 1;
  transform: translateY(0);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(1.5rem, 4vw, 3rem);
}

.feature {
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease, border-color 0.3s ease;
}

.feature.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.feature:nth-child(1) { transition-delay: 0s; }
.feature:nth-child(2) { transition-delay: 0.1s; }
.feature:nth-child(3) { transition-delay: 0.2s; }

.feature:hover {
  border-color: var(--accent-soft);
}

.feature-icon {
  width: 40px;
  height: 40px;
  margin-bottom: 1.25rem;
  color: var(--accent-soft);
}

.feature-icon svg {
  width: 100%;
  height: 100%;
}

.feature-title {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.feature-desc {
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.6;
}

@media (max-width: 700px) {
  .features-grid {
    grid-template-columns: 1fr;
  }
}

/* Footer */
.landing-footer {
  padding: 2rem clamp(1.5rem, 6vw, 6rem) 2.5rem;
  border-top: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.landing-footer p {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.landing-footer a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s ease;
}

.landing-footer a:hover {
  color: var(--text);
}

.landing-footer-links {
  display: flex;
  gap: 1.5rem;
}