/* ============================================================
   Stacks — landing page styles
   Dark, minimal, jan.ai-inspired. Animations kept subtle.
   ============================================================ */

:root {
  --bg:        #0a0a0c;
  --bg-soft:   #0f1014;
  --surface:   #141519;
  --surface-2: #1a1c21;
  --border:    rgba(255, 255, 255, 0.08);
  --border-2:  rgba(255, 255, 255, 0.14);
  --text:      #f4f4f6;
  --text-2:    #a3a3ad;
  --text-3:    #6e6e78;
  --accent:    #6d8bff;
  --accent-2:  #9b6dff;
  --accent-ink:#0a0a0c;
  --radius:    14px;
  --maxw:      1120px;
  --ease:      cubic-bezier(0.22, 1, 0.36, 1);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei",
    "PingFang SC", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

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

h1, h2, h3 { line-height: 1.15; letter-spacing: -0.02em; font-weight: 650; }

/* ── Buttons ── */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 18px;
  border-radius: 10px;
  font-size: 14px; font-weight: 550;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.18s var(--ease), background 0.18s var(--ease),
    border-color 0.18s var(--ease), box-shadow 0.18s var(--ease);
  white-space: nowrap;
}
.btn:active { transform: translateY(1px) scale(0.99); }
.btn-lg { padding: 13px 26px; font-size: 15px; border-radius: 12px; }
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-ink);
  box-shadow: 0 6px 22px -8px rgba(109, 139, 255, 0.6);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 12px 30px -10px rgba(109, 139, 255, 0.7); }
.btn-ghost {
  background: rgba(255, 255, 255, 0.04);
  border-color: var(--border-2);
  color: var(--text);
}
.btn-ghost:hover { background: rgba(255, 255, 255, 0.09); transform: translateY(-2px); }

/* ── Nav ── */
.nav {
  position: sticky; top: 0; z-index: 50;
  transition: background 0.25s var(--ease), border-color 0.25s var(--ease);
  border-bottom: 1px solid transparent;
}
.nav.scrolled {
  background: rgba(10, 10, 12, 0.72);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 14px 24px;
  display: flex; align-items: center; gap: 24px;
}
.brand { display: inline-flex; align-items: center; gap: 9px; font-weight: 650; font-size: 16px; }
.brand-logo { border-radius: 8px; object-fit: contain; }
.brand-logo-sm { border-radius: 5px; object-fit: contain; vertical-align: middle; }
.nav-links { display: flex; gap: 22px; margin-left: 12px; }
.nav-links a { color: var(--text-2); font-size: 14px; transition: color 0.15s; }
.nav-links a:hover { color: var(--text); }
.nav-actions { margin-left: auto; display: flex; align-items: center; gap: 10px; }

/* ── Hero ── */
.hero {
  max-width: var(--maxw); margin: 0 auto;
  padding: 72px 24px 40px;
  display: grid; grid-template-columns: 1.05fr 0.95fr;
  gap: 48px; align-items: center;
}
.eyebrow {
  display: inline-block; font-size: 13px; font-weight: 550;
  color: var(--accent); letter-spacing: 0.02em;
  padding: 5px 12px; border: 1px solid var(--border-2); border-radius: 999px;
  margin-bottom: 22px;
}
.hero h1 { font-size: clamp(38px, 5.4vw, 64px); margin-bottom: 22px; }
.lead { font-size: 17px; color: var(--text-2); max-width: 30em; margin-bottom: 30px; }
.lead strong { color: var(--text); font-weight: 600; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 26px; }
.trust { list-style: none; display: flex; flex-wrap: wrap; gap: 18px; font-size: 13px; color: var(--text-3); }
.trust li { display: inline-flex; align-items: center; gap: 7px; }
.trust .dot { width: 6px; height: 6px; border-radius: 50%; background: var(--accent); opacity: 0.8; }

/* ── Hero visual: stack mockup ── */
.hero-visual { position: relative; }
.desk {
  position: relative; aspect-ratio: 1 / 1; width: 100%;
  border-radius: 24px;
  background:
    radial-gradient(120% 120% at 80% 0%, rgba(109, 139, 255, 0.10), transparent 55%),
    radial-gradient(120% 120% at 0% 100%, rgba(155, 109, 255, 0.10), transparent 55%),
    var(--surface);
  border: 1px solid var(--border);
  padding: 28px;
  display: grid; grid-template-columns: 1fr 1fr; gap: 16px; align-content: center;
  overflow: hidden;
}
.pile {
  background: var(--surface-2);
  border: 1px solid var(--border-2);
  border-radius: 16px;
  padding: 14px;
  animation: floatIn 0.7s var(--ease) backwards;
  animation-delay: var(--d);
  transition: transform 0.25s var(--ease), border-color 0.25s var(--ease);
}
.pile:hover { transform: translateY(-4px); border-color: rgba(109, 139, 255, 0.4); }
.pile-head { display: flex; align-items: center; gap: 9px; font-size: 13px; font-weight: 550; color: var(--text); }
.pile-head em { margin-left: auto; font-style: normal; color: var(--text-3); font-size: 12px; }
.pile-body { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 12px; }
.chip { width: 30px; height: 22px; border-radius: 6px; background: rgba(255, 255, 255, 0.06); border: 1px solid var(--border); }
.chip:nth-child(2) { opacity: 0.7; }
.chip:nth-child(3) { opacity: 0.45; }
.ico { width: 14px; height: 14px; border-radius: 4px; display: inline-block; }
.ico-img { background: #2187f3; }
.ico-doc { background: #795548; }
.ico-vid { background: #9c27b0; }
.ico-zip { background: #8b572a; }
.cursor {
  position: absolute; width: 16px; height: 16px; right: 30%; bottom: 26%;
  border-right: 2px solid var(--text); border-bottom: 2px solid var(--text);
  transform: rotate(45deg);
  animation: blink 1.6s ease-in-out infinite;
}
@keyframes floatIn { from { opacity: 0; transform: translateY(14px) scale(0.97); } to { opacity: 1; transform: none; } }
@keyframes blink { 0%, 100% { opacity: 0.25; } 50% { opacity: 1; } }

/* ── Sections ── */
.section { max-width: var(--maxw); margin: 0 auto; padding: 84px 24px; }
.section-alt { max-width: none; background: var(--bg-soft); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-alt > * { max-width: var(--maxw); margin-left: auto; margin-right: auto; }
.section-head { text-align: center; margin-bottom: 52px; }
.section-head h2 { font-size: clamp(28px, 3.6vw, 40px); margin-bottom: 12px; }
.section-head p { color: var(--text-2); font-size: 16px; }

/* ── Feature grid ── */
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 26px 24px;
  transition: transform 0.22s var(--ease), border-color 0.22s var(--ease), background 0.22s var(--ease);
}
.card:hover { transform: translateY(-4px); border-color: var(--border-2); background: var(--surface-2); }
.card-ico { font-size: 26px; margin-bottom: 14px; }
.card h3 { font-size: 17px; margin-bottom: 8px; }
.card p { color: var(--text-2); font-size: 14px; }

/* ── Steps ── */
.steps { list-style: none; display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.steps li { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px 24px; }
.step-n {
  display: inline-grid; place-items: center; width: 30px; height: 30px;
  border-radius: 9px; font-weight: 650; font-size: 14px; margin-bottom: 14px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: var(--accent-ink);
}
.steps h3 { font-size: 16px; margin-bottom: 8px; }
.steps p { color: var(--text-2); font-size: 14px; }
.steps code { background: rgba(255, 255, 255, 0.07); padding: 1px 6px; border-radius: 5px; font-size: 12px; color: var(--text); }

/* ── Open source band ── */
.oss {
  display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 22px; padding: 44px;
}
.oss-text h2 { font-size: clamp(24px, 3vw, 34px); margin-bottom: 12px; }
.oss-text p { color: var(--text-2); margin-bottom: 22px; }
.oss-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.stat { background: var(--bg); border: 1px solid var(--border); border-radius: 14px; padding: 20px; text-align: center; }
.stat-num { display: block; font-size: 28px; font-weight: 650; background: linear-gradient(135deg, var(--accent), var(--accent-2)); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.stat-label { font-size: 12px; color: var(--text-3); margin-top: 4px; display: block; }

/* ── Final CTA ── */
.cta { padding: 90px 24px; }
.cta-inner {
  max-width: 760px; margin: 0 auto; text-align: center;
  background:
    radial-gradient(100% 140% at 50% 0%, rgba(109, 139, 255, 0.14), transparent 60%),
    var(--surface);
  border: 1px solid var(--border-2); border-radius: 26px; padding: 56px 32px;
}
.cta-inner h2 { font-size: clamp(26px, 3.4vw, 38px); margin-bottom: 10px; }
.cta-inner p { color: var(--text-2); margin-bottom: 26px; }

/* ── Footer ── */
.footer { border-top: 1px solid var(--border); }
.footer-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 24px;
  display: flex; align-items: center; gap: 16px; font-size: 13px; color: var(--text-3);
}
.footer-inner .brand { color: var(--text); }
.footer-inner .muted { margin-left: auto; }
.footer-inner a { color: var(--text-2); transition: color 0.15s; }
.footer-inner a:hover { color: var(--text); }

/* ── Reveal on scroll ── */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.6s var(--ease), transform 0.6s var(--ease); }
.reveal.in { opacity: 1; transform: none; }

/* ── Responsive ── */
@media (max-width: 880px) {
  .hero { grid-template-columns: 1fr; padding-top: 48px; gap: 36px; }
  .hero-visual { order: -1; max-width: 460px; margin: 0 auto; width: 100%; }
  .grid, .steps { grid-template-columns: 1fr; }
  .oss { grid-template-columns: 1fr; padding: 32px; }
  .nav-links { display: none; }
}
@media (max-width: 520px) {
  .oss-stats { grid-template-columns: 1fr 1fr; }
  .nav-actions .btn-ghost span, .nav-actions .btn-ghost { font-size: 13px; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
}