/* ============================================================
   Learning System Studio — style-landing.css
   Design: Linear-inspired · Deep Dark · Single Tone · Editorial
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&family=Noto+Sans+SC:wght@300;400;500&display=swap');

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

/* ── Tokens ── */
:root {
  --bg:           #0f0f10;
  --bg-elevated:  #161618;
  --bg-border:    #1e1e22;
  --bg-hover:     #1a1a1e;

  --text-primary:   #f0f0f2;
  --text-secondary: #8b8b99;
  --text-tertiary:  #55555f;

  --accent:       #6366f1;   /* indigo — trust + intelligence */
  --accent-dim:   rgba(99,102,241,0.12);
  --accent-glow:  rgba(99,102,241,0.06);

  --border:       rgba(255,255,255,0.07);
  --border-hover: rgba(255,255,255,0.13);

  --shell-w:   1040px;
  --shell-n:   660px;
  --gap:       clamp(4rem, 10vw, 7rem);

  --sans-en:  'Inter', sans-serif;
  --sans-zh:  'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --ease:     cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

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

body {
  font-family: var(--sans-zh);
  font-weight: 300;
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  /* Linear signature: subtle radial glow at top */
  background-image:
    radial-gradient(ellipse 80% 40% at 50% -10%, rgba(99,102,241,0.08) 0%, transparent 70%);
  background-attachment: fixed;
}

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

/* ── Shell ── */
.shell {
  max-width: var(--shell-w);
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 5vw, 2.5rem);
}
.shell.narrow { max-width: var(--shell-n); }
.shell.center { text-align: center; }

/* ══════════════════════════════════════
   HEADER
   ══════════════════════════════════════ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(15,15,16,0.75);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 0.9rem 0;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.logo a {
  font-family: var(--sans-en);
  font-weight: 500;
  font-size: 0.9rem;
  color: var(--text-primary);
  letter-spacing: -0.01em;
  white-space: nowrap;
}

nav.nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

nav.nav a {
  font-family: var(--sans-en);
  font-size: 0.8rem;
  font-weight: 400;
  color: var(--text-secondary);
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  transition: color 0.15s, background 0.15s;
}

nav.nav a:hover { color: var(--text-primary); background: var(--bg-hover); }
nav.nav a[href*="programs"] { color: var(--text-primary); }

/* ══════════════════════════════════════
   FOOTER
   ══════════════════════════════════════ */
.site-footer {
  padding: 4rem 0 2.5rem;
}

.site-footer .shell {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 2rem;
}

.footer-intro h3 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
}

.footer-intro p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.9;
  max-width: 260px;
}

.footer-nav {
  display: flex;
  flex-direction: row;
  gap: 1.2rem;
  align-items: center;
  justify-content: center;
}

.footer-nav a {
  font-size: 0.8rem;
  color: var(--text-tertiary);
  transition: color 0.2s ease, transform 0.2s ease;
}

.footer-nav a:hover {
  color: var(--text-primary);
  transform: translateX(2px);
}

.footer-cta {
  grid-column: 1 / -1;
  border-top: 1px solid var(--border);
  padding-top: 2rem;
  
  display: flex;
  flex-direction: column;
  
  align-items: center;
  justify-content: center;
  
  text-align: center;
  gap: 1rem;
}

.footer-cta p {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.footer-bottom {
  opacity: 0.6;
}

.footer-bottom p {
  font-size: 0.72rem;
  color: var(--text-tertiary);
}

/* ══════════════════════════════════════
   SHARED TYPOGRAPHY
   ══════════════════════════════════════ */

.hero-kicker {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--sans-en);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(99,102,241,0.2);
  padding: 0.3rem 0.75rem;
  border-radius: 999px;
  margin-bottom: 1.75rem;
}

.hero-title {
  font-family: var(--sans-zh);
  font-weight: 400;
  font-size: clamp(2rem, 5.5vw, 3.4rem);
  line-height: 1.4;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  /* Linear-style: subtle gradient on headline */
  background: linear-gradient(135deg, #f0f0f2 30%, #8b8b99 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(0.9rem, 2vw, 1.05rem);
  font-weight: 300;
  color: var(--text-secondary);
  line-height: 2;
  max-width: 480px;
}

.section-title {
  font-family: var(--sans-zh);
  font-weight: 400;
  font-size: clamp(1.5rem, 3.5vw, 2.2rem);
  line-height: 1.4;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #f0f0f2 40%, #8b8b99 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.cta-section .section-title { text-align: center; }

.section-desc {
  font-size: 0.93rem;
  font-weight: 300;
  color: var(--text-secondary);
  line-height: 2;
  max-width: 520px;
}
.cta-section .section-desc { text-align: center; margin-inline: auto; }

.divider {
  width: 2rem;
  height: 1px;
  background: var(--border-hover);
  margin-bottom: 2.5rem;
}

/* ── Button ── */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1.4rem;
  background: var(--accent);
  color: #fff;
  font-family: var(--sans-en);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.15s var(--ease),
              box-shadow 0.15s;
  box-shadow: 0 0 0 1px rgba(99,102,241,0.4),
              0 4px 20px rgba(99,102,241,0.25);
}
.btn-primary:hover {
  opacity: 0.9;
  transform: translateY(-1px);
  box-shadow: 0 0 0 1px rgba(99,102,241,0.5),
              0 8px 28px rgba(99,102,241,0.35);
  color: #fff;
}

.cta-section .btn-primary {
  margin-top: 2rem;
  display: block;
  width: fit-content;
  margin-inline: auto;
}

.site-footer .btn-primary {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-hover);
  box-shadow: none;
  padding: 0.55rem 1.2rem;
  font-size: 0.76rem;
}
.site-footer .btn-primary:hover {
  background: var(--bg-hover);
  border-color: var(--border-hover);
  box-shadow: none;
  color: var(--text-primary);
}

/* ══════════════════════════════════════
   PAGE SECTIONS — single dark tone,
   separated by borders only
   ══════════════════════════════════════ */

.hero {
  padding: calc(var(--gap) * 1.5) 0 var(--gap);
  border-bottom: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}

/* Hero glow orb — Linear signature */
.hero-programs::before {
  content: '';
  position: absolute;
  top: -12rem; left: 50%;
  transform: translateX(-50%);
  width: 60rem; height: 30rem;
  background: radial-gradient(ellipse, rgba(99,102,241,0.09) 0%, transparent 65%);
  pointer-events: none;
}

/* All content sections — same dark bg, border-separated */
section {
  padding: var(--gap) 0;
  border-bottom: 1px solid var(--border);
}

section:last-of-type { border-bottom: none; }

/* CTA subtle glow */
.cta-section {
  position: relative;
  overflow: hidden;
}
.cta-section::before {
  content: '';
  position: absolute;
  bottom: -8rem; left: 50%;
  transform: translateX(-50%);
  width: 40rem; height: 24rem;
  background: radial-gradient(ellipse, rgba(99,102,241,0.07) 0%, transparent 65%);
  pointer-events: none;
}

/* ── Problem Grid ── */
.problem-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  margin-top: 2rem;
}

.problem-card {
  padding: 2rem 1.75rem;
  font-size: 0.93rem;
  font-weight: 300;
  line-height: 1.85;
  color: var(--text-secondary);
  background: var(--bg-elevated);
  position: relative;
  transition: background 0.2s, color 0.2s;
}
.problem-card:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}
.problem-card::before {
  content: '';
  position: absolute;
  top: 1.75rem; left: 1.75rem;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0.5;
  transition: opacity 0.2s;
}
.problem-card:hover::before { opacity: 1; }

/* ── Transformation List ── */
.transformation-list { display: flex; flex-direction: column; margin-top: 0.5rem; }

.transform-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.4rem 0;
  border-bottom: 1px solid var(--border);
  font-size: clamp(0.875rem, 2vw, 0.975rem);
  font-weight: 300;
  color: var(--text-secondary);
  transition: color 0.15s;
}
.transform-item:first-child { border-top: 1px solid var(--border); }
.transform-item:hover { color: var(--text-primary); }

.transform-item span {
  color: var(--accent);
  font-size: 0.9rem;
  flex-shrink: 0;
  font-family: var(--sans-en);
}

/* ── Cards (method / target) ── */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  margin-top: 2.5rem;
}

.card {
  background: var(--bg-elevated);
  padding: 2rem 1.75rem;
  position: relative;
  transition: background 0.2s;
}
.card:hover { background: var(--bg-hover); }

.card-title {
  font-size: 0.93rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  line-height: 1.5;
  font-family: var(--sans-zh);
}
.card p {
  font-size: 0.83rem;
  color: var(--text-secondary);
  line-height: 1.9;
  font-weight: 300;
}

/* ── Light Cards (service mode — same dark, lighter border) ── */
.cards-light {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  margin-top: 2.5rem;
}

.card-light {
  background: var(--bg-elevated);
  padding: 2rem 1.75rem;
  transition: background 0.2s;
}
.card-light:hover { background: var(--bg-hover); }

.card-light .card-title {
  font-size: 0.93rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  font-family: var(--sans-zh);
}
.card-light p {
  font-size: 0.83rem;
  color: var(--text-secondary);
  line-height: 1.9;
  font-weight: 300;
}

/* ── Service Flow ── */
.service-flow { display: flex; flex-direction: column; margin-top: 0.5rem; }

.flow-item {
  display: grid;
  grid-template-columns: 3rem 1fr;
  align-items: start;
  gap: 1.25rem;
  padding: 1.6rem 0;
  border-bottom: 1px solid var(--border);
  transition: background 0.15s;
}
.flow-item:first-child { border-top: 1px solid var(--border); }

.flow-number {
  font-family: var(--sans-en);
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.05em;
  padding-top: 0.25rem;
  opacity: 0.7;
}

.flow-item h3 {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
  font-family: var(--sans-zh);
}
.flow-item p {
  font-size: 0.83rem;
  color: var(--text-secondary);
  font-weight: 300;
}

/* ── CTA note ── */
.cta-note {
  margin-top: 1rem;
  font-size: 0.78rem;
  color: var(--text-tertiary);
}

/* ══════════════════════════════════════
   ANIMATIONS
   ══════════════════════════════════════ */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(1rem); }
  to   { opacity: 1; transform: translateY(0); }
}

.hero-kicker   { animation: fadeUp 0.6s 0.05s var(--ease) both; }
.hero-title    { animation: fadeUp 0.6s 0.15s var(--ease) both; }
.hero-subtitle { animation: fadeUp 0.6s 0.28s var(--ease) both; }

.problem-card:nth-child(1) { animation: fadeUp 0.5s 0.08s var(--ease) both; }
.problem-card:nth-child(2) { animation: fadeUp 0.5s 0.16s var(--ease) both; }
.problem-card:nth-child(3) { animation: fadeUp 0.5s 0.24s var(--ease) both; }
.problem-card:nth-child(4) { animation: fadeUp 0.5s 0.32s var(--ease) both; }

.transform-item:nth-child(1) { animation: fadeUp 0.5s 0.06s var(--ease) both; }
.transform-item:nth-child(2) { animation: fadeUp 0.5s 0.14s var(--ease) both; }
.transform-item:nth-child(3) { animation: fadeUp 0.5s 0.22s var(--ease) both; }

.card:nth-child(1) { animation: fadeUp 0.5s 0.06s var(--ease) both; }
.card:nth-child(2) { animation: fadeUp 0.5s 0.14s var(--ease) both; }
.card:nth-child(3) { animation: fadeUp 0.5s 0.22s var(--ease) both; }
.card:nth-child(4) { animation: fadeUp 0.5s 0.30s var(--ease) both; }

.card-light:nth-child(1) { animation: fadeUp 0.5s 0.06s var(--ease) both; }
.card-light:nth-child(2) { animation: fadeUp 0.5s 0.14s var(--ease) both; }
.card-light:nth-child(3) { animation: fadeUp 0.5s 0.22s var(--ease) both; }

.flow-item:nth-child(1) { animation: fadeUp 0.5s 0.06s var(--ease) both; }
.flow-item:nth-child(2) { animation: fadeUp 0.5s 0.14s var(--ease) both; }
.flow-item:nth-child(3) { animation: fadeUp 0.5s 0.22s var(--ease) both; }

/* ══════════════════════════════════════
   RESPONSIVE
   ══════════════════════════════════════ */
@media (max-width: 720px) {
  nav.nav a { font-size: 0.75rem; padding: 0.35rem 0.5rem; }
  .problem-grid { grid-template-columns: 1fr 1fr; }
  .cards, .cards-light { grid-template-columns: 1fr; }
  .site-footer .shell { grid-template-columns: 1fr; }
  .footer-nav { align-items: center; justify-content: center;}
  .footer-cta { flex-direction: column; align-items: center; text-align: center; }
}

@media (max-width: 440px) {
  .problem-grid { grid-template-columns: 1fr; }
  nav.nav { gap: 0; }
  nav.nav a { font-size: 0.68rem; padding: 0.3rem 0.4rem; }
}

@media print {
  body { background: white; color: black; }
  .btn-primary { display: none; }
  .site-header { position: static; }
}

body {
  background: #0f0f10 !important;
}